Offshore Mooring Systems for Wind Turbines

The objective of this paper is to carry out response analyses eight floating wind turbines and compare them together; something that not seen in previous research papers. From perspective, will the offset regarding motions six degrees freedom respective turbines. applied forces these consider come mainly from constant on turbines blades, as well waves currents. Different values are considered compared different speeds, velocities This also provides various innovative references related turbine software. Validation verification studies left for future work due complexity data provided paper. However, some comparisons made between obtained analysis results external references. mentioned unfortunately have with wave environmental conditions, power capacities, dimensional characteristics. dynamic studied shown maximum surge, sway, heave corresponds DTU Spar 1 turbine. roll yaw INO-WINDMOOR pitch WindFloat aero-hydro-servo-elastic method was used Sima software run analyses. It a time-domain analysis, it uses meters [m] [] describe offsets support structures

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A floating offshore wind power system that reduces yaw motion to improve power generation efficiency. The system uses a triangular floating body with three columns connected by pontoons. The wind turbine is mounted on one column. The mooring lines connecting the floating body to the seabed form a Y shape when viewed from above, reducing yaw motion compared to conventional X-shaped moorings.

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In recent years, the twin-barge float-over method has been widely used in offshore installations. This paper conducts numerical simulation and experimental research on installation of wind turbines (TBFOI-OWTs), focusing primarily seakeeping performance, also explores influence gap distance hydrodynamic behavior TBFOI-OWTs. Model tests are conducted ocean basin at Tsinghua Shenzhen International Graduate School. A physical model with a scale ratio 1:50 is designed fabricated, comprising two barges, truss carriage frame, small turbines, spread catenary mooring system. series tests, including free decay regular wave random carried out to investigate hydrodynamics The results good agreement, thereby validating accuracy method. motion RAOs TBFOI-OWTs small, demonstrating their performance. Compared situation, surge sway motions waves have greater ranges amplitudes. reveals that analysis cannot depend only, more importantly, nature realistic less favorable for responses controlled by motions natural frequencies incident frequency. It revealed between barges significant beam seas. Withi... Read More

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ABSTRACT This study presents an experimental investigation into the influence of anchorsoil interaction on dynamic behaviour tension leg platform (TLP)type floating wind turbines. A 1/100 scale model NREL 5MW reference turbine was fabricated using a 3D printer, with scaling parameters determined based Froude laws to ensure similarity between and prototype. comprehensive discussion applied principles is provided, along detailed description calibration procedures for customdeveloped sixaxis sensors used in experiments. Free vibration tests were performed scaled evaluate different anchoring systemssuction caissons, triplesuction caissons gravity anchorsunder varying seabed conditions. Throughout experiments, installed both nacelle within captured timedependent accelerations x , y z directions, as well rotational responses about same axes. To robustness repeatability results, each test conducted minimum three times, mitigating potential uncertainties. The findings demonstrated pronounced systems conditions dominant surge pitch frequencies model. Specifically, r... Read More

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Abstract. Floating offshore wind turbine (FOWT) systems are subject to complex environmental loads, with significant potential for damage in extreme storm conditions. Design simulations these conditions required assess the survivability of device some level confidence. Aero-hydro-servo-elastic engineering tools can be used a reasonable balance accuracy and computational efficiency. The models require many input parameters describe air water conditions, system properties, load calculations. Each has possible range, due either statistical uncertainty or variations time. Variation have important effects on resulting but it is not practical perform detailed assessments impact this every parameter. This work demonstrates method identify that most loads focus further inspection. process done specifically cases defined International Electrotechnical Commission design requirements floating turbines. analysis was performed using Energy Agency Wind 15 MW reference atop University Maine VolturnUS-S platform two US regions, Gulf Humboldt Bay. It found direction incident waves current, yaw misali... Read More

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Floating platform and installation method for reducing construction and installation costs of offshore platforms by using taut mooring and containing heavy materials in containers placed on the seafloor. The platform has a floating structure to support a tower, connected by tethers to an anchor structure with containers filled with materials like soil or gravel. The containers are fixed to the tethers and placed on the seabed. This allows the platform to be moored by tensioning the tethers to pull the floating structure into the water. The heavy contents of the containers provide the platform weight and stability without needing extensive concrete structures.

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The increasing demand for renewable energy sources has prompted significant interest in exploring offshore wind power. However, most of the studies literature are limited to onshore power generation with a lack long-term data from wide range operational turbines. This research explores design considerations and factors influencing Floating Offshore Wind Turbine (FOWT) by providing valuable insights into key areas that attention, thereby facilitating realization full performance FOWTs. While FOWTs present promising solution harnessing deep waters, challenges need be addressed. These include foundations can withstand harsh marine conditions, development effective strategies fabrication, installation, operation, maintenance decommissioning integration these comprehensive framework. specific guidelines standards further complicates issues. paper aims explore detail propose innovative solutions advance commercialization In this work, numerical simulations modelling techniques employed analyse dynamic response under various environmental conditions. FOWT transportation installation were br... Read More

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A novel towerless floating wind turbine (TFW) is proposed in this study and integrated with three wave energy converters (WECs) by the hinge joint to further increase stability of system. This aims reduce large pitch accelerations for nacelle excessive stresses at tower base when encountering amplitude waves. Based on numerical tests performed viscous corrected panel method, it revealed that in-phase excitation forces acting columns can result largest mooring tension short-period waves high-frequency oscillation appeared under specific conditions attributed triple-frequency components. The motion TFW platform be largely suppressed mitigating adverse effect induced superstructure. Hit abnormal wave, exhibits a significant hysteresis phenomenon maximum response due multi-system coupling effect. Compared traditional DeepCwind platform, survivability extreme sea states greatly improved, considering responses snap loads have been reduced transient stage, durations heave become much shortened decaying stage. enhanced integrating hinged WECs condition larger power-takeoff damping force but ... Read More

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A stability control system for large-scale offshore wind turbines mounted on semi-submersible floating foundations. The system uses sensors to monitor environmental factors like waves, wind, and currents, as well as the motion responses of the wind turbine and floating foundation. It integrates these data into a digital twin model to predict stability during storms. The system proactively adjusts mooring chain tension and ballast water levels before the storm to stabilize the floating foundation and prevent excessive motion. This improves stability compared to passive control methods that only respond during storms.

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Mooring system for shallow water floating wind turbines using tension leg platforms (TLPs) that provides stability and positioning without the need for large columns. The system has a central suction anchor on the seabed below the TLP, surrounded by distributed suction anchors. The TLP columns connect to tension moorings that converge at the central anchor and disperse anchors. This configuration provides stability through tension balance without requiring buoyancy from large columns.

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Shallow water mooring system for floating offshore wind turbines that improves stability in deep waters where fixed foundations are impractical. The mooring system uses tension legs, a balancing device, and a fixed block to prevent tilting and roll from ocean waves. The base has tension legs anchored to the seafloor, a fixed component for the wind turbine, and a balancing device inside. When the turbine tilts, a pressure chamber injects seawater into a receiver to counterbalance and stabilize the base. The fixed block has an indented section to prevent erosion from waves. This allows floating wind turbines to operate in deeper waters without being driven off course by wave action.

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Mooring system for floating offshore wind turbines that provides more even tension on the mooring lines to prevent loosening and damage. The system uses a rotating turret on the wind turbine foundation that transmits centrifugal force to the four mooring lines at the corners when the turbine rotates. This equalizes the tension on all four lines instead of just the one on the stressed side. This prevents loosening and breakage of the mooring lines when the turbine experiences lateral forces.

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A tensioned wind turbine foundation for offshore wind farms that can be anchored to rock seabeds in deep waters. The foundation has a rock anchoring system, a mooring cable, a semi-submersible module, a tower, and a wind turbine. The rock anchoring system attaches to the seabed rock formations. The mooring cable secures the foundation to the seabed. The semi-submersible module floats on the water and supports the tower and turbine. This allows deploying wind turbines in deep water areas without requiring expensive gravity foundations or complex pile driving. The tensioned foundation can be anchored to existing rock formations instead of requiring extensive seabed leveling or drilling. It reduces costs and simplifies construction compared to traditional foundations in challenging offshore environments.

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Group mooring of multiple floating offshore wind turbines together in a designated area at sea. The group mooring uses a mass mooring facility with concrete heavy structures arranged in a grid on the seabed. The turbines are moored to some of the concrete structures using lines. This allows multiple turbines to be moored in a grid pattern without collisions. It provides a centralized location for multiple turbines instead of individual moorings. This saves space compared to stacking turbines on land between productions.

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Tension devices for mooring lines of offshore wind turbines that provide constant tension in the mooring lines as the turbine moves in waves. The devices aim to prevent the turbine from being dragged by varying line tensions in different weather conditions. One device uses a float and weight that are neutrally buoyant when connected. Another device uses a parallelogram linkage with a weight and float that provides a force that increases slowly as the turbine moves. Both devices aim to maintain a constant force in the mooring lines even when the turbine isn't moving.

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A tension leg type offshore wind power platform that can be assembled and installed on land before being towed to sea. The platform consists of a wind turbine, tower, center buoy, extended section, and cable assembly. It connects to mooring anchors using a locking mechanism on the platform. The locking mechanism allows tensioning the mooring chain by adjusting ballast in the buoys. This eliminates the need for external cranes or boats to connect the platform to the moorings at sea, reducing costs.

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Single point mooring system for offshore floating wind turbines that allows the floating platform to rotate around a central turret for alignment with the wind without a yaw mechanism. The floating body has connecting components at intervals that can rotate relative to the body. The wind turbine is fixed on the body and connected to a cable. Each connecting component connects a mooring cable to anchor. This allows the body to rotate while keeping the turbine aligned. The turret has bearings for rotation and an electric slip ring for power transmission. An anchor windlass retracts and releases the mooring chain.

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A device to optimize the mooring of floating platforms in offshore wind farms to improve stability and reduce risk of failure. The device uses a closed transmission chain between the platform and anchor block. A ballast block is connected to one end of the chain near the platform. The chain is routed through a pulley. By adjusting the position of the ballast block, the chain angle and tension can be changed. This allows controlled variation in the restoring moment provided by the mooring tension. It helps balance forces on the platform in extreme conditions and prevent overturning.

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Offshore wind turbine foundation design to improve stability and bearing capacity in deeper waters. The foundation uses a collar around the top of the pile, hydraulic cylinders attached to the collar, tension sensors on the cylinders, and mooring cables connecting the cylinders to anchor foundations. The hydraulic cylinders can adjust the tension in the mooring lines to counteract bending and tilting forces on the pile from wind and waves. This provides additional horizontal resistance to stabilize the pile in deeper waters where traditional single piles may not be sufficient.

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A compliant mooring hybrid floating wind turbine platform that provides a small mooring radius, low cost, good stability, and ease of installation compared to existing floating wind turbine platforms. The platform has a semi-submersible foundation, tower, wind turbine, and compliant mooring device. The compliant mooring allows adjusting mooring line length and ballast level to mitigate extreme loads on the mooring anchors. This reduces anchor chain tension and improves stability. The compliant mooring also allows compact mooring layouts compared to catenary anchors. The platform can be towed, installed, operated, maintained, stabilized, and recovered in stages.

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