scholarly journals Mooring System Design and Verification for a Floating Vertical Axis Wind Turbine

2020 ◽  
Vol 11 (03) ◽  
pp. 2050003
Author(s):  
Fausto Raschioni ◽  
Roberto Longo ◽  
Ali Mehmanparast ◽  
Cesare Mario Rizzo
Keyword(s):  
Wind Turbine ◽  
Limit State ◽  
Vertical Axis ◽  
Future Application ◽  
Ultimate Limit State ◽  
Mooring System ◽  
Vertical Axis Wind Turbine ◽  
Floating Wind Turbine ◽  
Crucial Part ◽  
Ultimate Limit

The aim of this study is to investigate the technical feasibility of an innovative vertical axis floating wind turbine concept with the main focus on the design and verification of the mooring system. The study is developed through iterative processes in order to identify the optimum design for the new floating wind turbine concept. The Ultimate Limit State (ULS) criteria have been considered to verify the integrity of the mooring system in the extreme environmental conditions with a 50-year return period. For this purpose, time domain dynamic analysis has been performed using the commercial software OrcaFlex [Orcina website, OrcaFlex software, https://www.orcina.com/ ]. Although the analysis is carried out for a specific site deemed suitable for the project, the results can be used as an input for any future application in other locations. The present study is intended to be a proof of concept with a proposed scientific framework for optimization of the mooring system which is considered to be a crucial part in the design of floating wind turbines due to their complex dynamic behavior.

System reliability evaluation of mooring system for fish cage under ultimate limit state

2019 ◽  
Vol 172 ◽  
pp. 422-433 ◽  
Author(s):  
Hui-Min Hou ◽  
Guo-Hai Dong ◽  
Tiao-Jian Xu ◽  
Yun-Peng Zhao
Keyword(s):  
System Reliability ◽  
Limit State ◽  
Reliability Evaluation ◽  
Ultimate Limit State ◽  
Mooring System ◽  
Ultimate Limit

scholarly journals Ultimate Limit State Risk Assessment of Penta Pod Suction Bucket Support Structures for Offshore Wind Turbine due to Scour

2021 ◽  
Vol 33 (6) ◽  
pp. 374-382
Author(s):  
Young Jin Kim ◽  
Ngo Duc Vu ◽  
Dong Hyawn Kim
Keyword(s):  
Risk Assessment ◽  
Wind Turbine ◽  
Limit State ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Ultimate Limit State ◽  
Support Structures ◽  
Significant Wave ◽  
Scour Hazard ◽  
Ultimate Limit

The scour risk assessment was conducted for ultimate limit state of newly developed penta pod suction bucket support structures for a 5.5 MW offshore wind turbine. The hazard was found by using an empirical formula for scour depth suitable for considering marine environmental conditions such as significant wave height, significant wave period, and current velocity. The scour fragility curve was calculated by using allowable bearing capacity criteria of suction foundation. The scour risk was assessed by combining the scour hazard and the scour fragility.

Innovation for a Reduction of the Yaw Moment on a Floating Platform With a Vertical-Axis Wind Turbine

2014 ◽  
Author(s):  
Samuel Kanner ◽  
Ronald W. Yeung
Keyword(s):  
Wind Turbine ◽  
Translational Motion ◽  
Vertical Axis ◽  
Mooring System ◽  
Vertical Axis Wind Turbine ◽  
Spar Platform ◽  
Advantages And Disadvantages ◽  
The Third ◽  
Lead Screw ◽  
Novel Design

Three designs of a floating spar platform for a vertical-axis wind turbine (VAWT) are considered, including two novel designs. The novel designs convert the rotary motion of the platform to a translational motion (namely, heave), to reduce the maximum yaw stiffness requirements of the mooring system. In typical operational conditions of a VAWT, the mooring system needs to be stiff to prevent the yaw rotation of the platform, allowing power to be taken off from the rotary electromagnetic generator. The first design considered is a simple spar platform with mooring lines in a spread-mooring configuration. The second design, a novel design, incorporates a lead-screw to couple the rotational motion to a translational motion. This design can take advantage of the hydrostatic restoring force present in heave to reduce the mooring stiffness. The third design, also a novel design, uses a spar-torus combination platform and a lead-screw to counteract the torque on the stator of the generator. Numerical models in the time domain are developed to simulate the dynamics of these three platforms in regular waves and constant-wind conditions and the results are reported. It was found that the stiffness requirements of the second design can be reduced by 25% without changing the transient dynamics. If the wave climate is energetic enough, the third design can not only reduce the yaw stiffness requirements but also increase the mean power produced. Advantages and disadvantages of each design due to the relative complexity of each system, as well as the mooring, generator, and platform dynamics are discussed.

Modelling and Analysis of a Semi-Submersible Wind Turbine With a Central Tower With Emphasis on the Brace System

2013 ◽  
Author(s):  
Chenyu Luan ◽  
Zhen Gao ◽  
Torgeir Moan
Keyword(s):  
Wind Turbine ◽  
Time Domain ◽  
Elastic System ◽  
State Of The Art ◽  
Limit State ◽  
Modeling Method ◽  
Ultimate Limit State ◽  
The Novel ◽  
Floating Wind Turbine ◽  
The Time Domain

This paper deals with analysis of the OC4 DeepCWind semi-submersible wind turbine, which is provided by NREL through the OC4 project. This concept is a three-column semi-submersible supporting a 5 MW wind turbine on an additional central column. The fact that the semi-submersible floater needs a large water line restoring moment to achieve sufficient stability and the control of the cost based on the steel weight make the design of braces and pontoons very challenging. Effective methods are needed to check the strength of the brace system based on the response forces and moments in the braces under different design environmental conditions, while the floating wind turbine is needed to be considered as an aero-hydro-servo-elastic system. A novel modeling methodology based on the code Simo/Riflex is introduced in this paper. Simo/Riflex is a state-of-the-art code that can account for the coupling effect between rigid body motions and slender structures (e.g. mooring lines, braces and blades) in the time-domain. Simo/Riflex can be combined with Aerodyn, which is a state-of-the-art aerodynamic code, to model the floating wind turbine as an aero-hydro-servo-elastic system, as well as be combined with simplified aerodynamic codes (e.g.TDHMILL) to improve the efficiency of the numerical simulation. The novel modeling method can give the forces and moments in the brace system of the floater under hydrodynamic and aerodynamic loads in the time-domain. In order to get the structural response of the braces, the side columns and the central supporting column are modeled as independent rigid bodies in Simo while the braces are modeled by beam elements in Riflex. Master and slave relationship is applied at the joints in between of the columns and braces. As an application example, the novel modeling method based on the code Simo/Riflex+TDHMILL, which is capable of modeling the floating wind turbine as an aero-hydro-elastic system, has been used to carry out Ultimate Limit State (ULS) design check for the brace system of the OC4 DeepCWind semi-submersible wind turbine based on relevant standards, i.e. NORSOK N00-3, NORSOK N-004, IEC61400-1, IEC61400-3. The modeling method can also be used by other codes which have similar features as Simo/Riflex.

Conceptual Design of a Floating Support Structure and Mooring System for a Vertical Axis Wind Turbine

2012 ◽  
Author(s):  
Petter Andreas Berthelsen ◽  
Ivar Fylling ◽  
Luca Vita ◽  
Uwe S. Paulsen
Keyword(s):  
Wind Turbine ◽  
Conceptual Design ◽  
Optimization Problems ◽  
Vertical Axis ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Response Analysis ◽  
Mooring System ◽  
Vertical Axis Wind Turbine ◽  
Support Structure

This paper deals with the conceptual design of a floating support structure and mooring system for a 5MW vertical axis offshore wind turbine. The work is carried out as part of the DeepWind project, where the main objective is to investigate the feasibility of a floating vertical axis offshore wind turbine. The DeepWind concept consists of a Darrieus rotor mounted on a spar buoy support structure. The conceptual design is carried out in an iterative process, involving the different subcomponents. The present work is part of the first design iteration and the objective is to find a feasible floating support structure and mooring system for the DeepWind concept. The conceptual design is formulated as an optimization problem: Starting with an initial configuration, the optimization procedure tries to find a cheaper solution while satisfying a set of design requirements. This approach utilizes available response analysis programs for mooring system forces and vessel motions, and combines this with a gradient search method for solution of nonlinear optimization problems with arbitrary constraints. Two different mooring system configurations are considered: Chain systems with 3 and 6 lines, respectively.

Calculating the aerodynamics of vertical axis wind turbines

2012 ◽  
Vol 34 (3) ◽  
pp. 169-184 ◽  
Author(s):  
Hoang Thi Bich Ngoc
Keyword(s):  
Wind Turbine ◽  
Incidence Angle ◽  
Vertical Axis ◽  
Rotor Blades ◽  
Vertical Axis Wind Turbine ◽  
Horizontal Axis Wind Turbine ◽  
Velocity Triangle ◽  
Relationship Of ◽  
The Relationship

Vertical axis wind turbine technology has been applied last years, very long after horizontal axis wind turbine technology. Aerodynamic problems of vertical axis wind machines are discussible. An important problem is the determination of the incidence law in the interaction between wind and rotor blades. The focus of the work is to establish equations of the incidence depending on the blade azimuth, and to solve them. From these results, aerodynamic torques and power can be calculated. The incidence angle is a parameter of velocity triangle, and both the factors depend not only on the blade azimuth but also on the ratio of rotational speed and horizontal speed. The built computational program allows theoretically selecting the relationship of geometric parameters of wind turbine in accordance with requirements on power, wind speed and installation conditions.

Design and Analysis of Vertical Axis Wind Turbine

2017 ◽  
Author(s):  
Prof. R.K. Bhoyar ◽  
Prof. S.J. Bhadang ◽  
Prof. N.Z. Adakane ◽  
Prof. N.D. Pachkawade
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine
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