Variational Modelling of Wave-Structure Interactions for Offshore Wind Turbines

2016 ◽  
Author(s):  
Tomasz Salwa ◽  
Onno Bokhove ◽  
Mark A. Kelmanson
Keyword(s):  
Variational Principle ◽  
Water Waves ◽  
Variational Approach ◽  
Coupled Model ◽  
Elastic Beam ◽  
Wave Structure ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Starting Point ◽  
Fully Coupled

We consider the development of a mathematical model of water waves interacting with the mast of an offshore wind turbine. A variational approach is used for which the starting point is an action functional describing a dual system comprising a potential-flow fluid, a solid structure modelled with (linear) elasticity, and the coupling between them. The variational principle is applied and discretized directly using Galerkin finite elements that are continuous in space and dis/continuous in time. We develop a linearized model of the fluid-structure or wave-mast coupling, which is a linearization of the variational principle for the fully coupled nonlinear model. Our numerical results indicate that our variational approach yields a stable numerical discretization of a fully coupled model of water waves and a linear elastic beam. The energy exchange between the subsystems is seen to be in balance, yielding a total energy that shows only small and bounded oscillations whose amplitude tends to zero as the timestep goes to zero.

scholarly journals Development and Verification of an Aero-Hydro-Servo-Elastic Coupled Model of Dynamics for FOWT, Based on the MoWiT Library

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1974
Author(s):  
Mareike Leimeister ◽  
Athanasios Kolios ◽  
Maurizio Collu
Keyword(s):  
Wind Turbine ◽  
International Energy Agency ◽  
Coupled Model ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
System Behavior ◽  
Energy Agency ◽  
Realistic Representation ◽  
Non Linear System ◽  
Fully Coupled

The complexity of floating offshore wind turbine (FOWT) systems, with their coupled motions, aero-hydro-servo-elastic dynamics, as well as non-linear system behavior and components, makes modeling and simulation indispensable. To ensure the correct implementation of the multi-physics, the engineering models and codes have to be verified and, subsequently, validated for proving the realistic representation of the real system behavior. Within the IEA (International Energy Agency) Wind Task 23 Subtask 2 offshore code-to-code comparisons have been performed. Based on these studies, using the OC3 phase IV spar-buoy FOWT system, the Modelica for Wind Turbines (MoWiT) library, developed at Fraunhofer IWES, is verified. MoWiT is capable of fully-coupled aero-hydro-servo-elastic simulations of wind turbine systems, onshore, offshore bottom-fixed, or even offshore floating. The hierarchical programing and multibody approach in the object-oriented and equation-based modeling language Modelica have the advantage (over some other simulation tools) of component-based modeling and, hence, easily modifying the implemented system model. The code-to-code comparisons with the results from the OC3 studies show, apart from expected differences due to required assumptions in consequence of missing data and incomplete information, good agreement and, consequently, substantiate the capability of MoWiT for fully-coupled aero-hydro-servo-elastic simulations of FOWT systems.

Dynamic analysis of 10 MW monopile supported offshore wind turbine based on fully coupled model

2021 ◽  
Vol 234 ◽  
pp. 109346
Author(s):  
Renqiang Xi ◽  
Xiuli Du ◽  
Piguang Wang ◽  
Chengshun Xu ◽  
Endi Zhai ◽  
...  
Keyword(s):  
Dynamic Analysis ◽  
Wind Turbine ◽  
Coupled Model ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Fully Coupled

The Current Situation and Recent Advances of Deep-Water Floating Wind Turbine

2012 ◽  
Vol 226-228 ◽  
pp. 772-775
Author(s):  
Yu Chen ◽  
Chun Li ◽  
Wei Gao ◽  
Jia Bin Nie
Keyword(s):  
Wind Turbine ◽  
Deep Water ◽  
Rapid Development ◽  
Coupled Model ◽  
Wind Farms ◽  
International Standards ◽  
Offshore Wind ◽  
Current Status ◽  
Offshore Wind Turbine ◽  
Floating Wind Turbine

Offshore wind turbine is a novel approach in the field of wind energy technology. With the rapid development of coastal wind farms, it is the trend to move them outward to deep-water district. However, the cost of construction rises significantly with the increase in water depth. Floating wind turbine is one of the efficient methods to solve this problem. The early history, current status and cutting-edge improvements of overseas offshore floating wind turbine as well as the shortcomings shall be presented. The concept designs, international standards, fully coupled model simulations and hydrodynamic experiments will be illustrated and discussed together with the development of the theory and the related software modules. Thus a novel researching method and concept shall be presented to provide reference for future researches

scholarly journals Dynamic Responses of a Jacket-Type Offshore Wind Turbine Using Decoupled and Coupled Models

2014 ◽  
Author(s):  
Muk Chen Ong ◽  
Erin E. Bachynski ◽  
Ole D. Økland ◽  
Elizabeth Passano
Keyword(s):  
Wind Turbine ◽  
Coupled Model ◽  
Dynamic Responses ◽  
Time Dependent ◽  
Offshore Wind ◽  
Wind Loads ◽  
Offshore Wind Turbine ◽  
Coupled Models ◽  
Thrust And Torque ◽  
Rotor Model

This paper presents numerical studies of the dynamic responses of a jacket-type offshore wind turbine using both decoupled and coupled models. In the decoupled (hydroelastic) model, the wind load is included through time-dependent forces and moments at a single node on the top of the tower. The coupled model is a hydro-servo-aero-elastic representation of the system. The investigated structure is the OC4 (Offshore Code Comparison Collaboration Continuation) jacket foundation supporting the NREL 5-MW wind turbine in a water depth of 50m. Different operational wind and wave loadings at an offshore site with relatively high soil stiffness are investigated. The objective of this study is to evaluate the applicability of the computationally efficient linear decoupled model by comparing with the results obtained from the nonlinear coupled model. Good agreement was obtained in the eigen-frequency analysis, decay tests, and wave-only simulations. In order to obtain good results in the combined wind and wave simulations, two different strategies were applied in the decoupled model, which are 1) Wind loads obtained from the coupled model were applied directly as time-dependent point loads in the decoupled model; and 2) The thrust and torque from an isolated rotor model were used as wind loads on the decoupled model together with a linear aerodynamic damper. It was found that, by applying the thrust force from an isolated rotor model in combination with linear damping, reasonable agreement could be obtained between the decoupled and coupled models in combined wind and wave simulations.

Progress on the Development of a Holistic Coupled Model of Dynamics for Offshore Wind Farms: Phase I — Aero-Hydro-Servo-Elastic Model, With Drive Train Model, for a Single Wind Turbine

2018 ◽  
Author(s):  
Z. Lin ◽  
D. Cevasco ◽  
M. Collu
Keyword(s):  
Wind Turbine ◽  
Failure Mode ◽  
Wind Turbines ◽  
Wind Farm ◽  
Failure Modes ◽  
Coupled Model ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Elastic Model ◽  
Offshore Wind Turbines

Currently, around 1500 offshore wind turbines are operating in the UK, for a total of 5.4GW, with further 3GW under construction, and 13GW consented. Until now, the focus of the research on offshore wind turbines has been mainly on how to minimise the CAPEX, but Operation and maintenance (O&M) can represent up to 39% of the lifetime costs of an offshore wind farm, due mainly to the high cost of the assets and the harsh environment, limiting the access to these assets in a safe mode. The present work is a part of a larger project, called HOME Offshore (www.homeoffshore.org), and it has as aim an advanced interpretation of the fault mechanisms through a holistic multiphysics modelling of the wind farm. The first step (presented here) toward achieving this aim consists of two main tasks: first of all, to identify and rank the most relevant failure modes within a wind farm, identifying the component, its mode of failure, and the relative environmental conditions. Then, to assess (for each failure mode) how the full-order, nonlinear model of dynamics used to represent the dynamics of the wind turbine can be reduced in order, such that is less computationally expensive (and therefore more suitable to be scaled up to represent multiple wind turbines), but still able to capture and represent the relevant dynamics linked with the inception of the chosen failure mode. A methodology to rank the failure modes is presented, followed by an approach to reduce the order of the Aero-Hydro-Servo-Elastic (AHSE) model of dynamics adopted. The results of the proposed reduced-order models are discussed, comparing it against the full-order coupled model, and taking as case study a fixed offshore wind turbine (monopile) in gearbox failure condition.

Numerical and Experimental Investigation of the Wave Loading on a Three-Legged Offshore Wind Turbine Jacket Platform

2018 ◽  
Author(s):  
Ioannis K. Chatjigeorgiou ◽  
Konstantinos Chatziioannou ◽  
Vanessa Katsardi ◽  
Apostolos Koukouselis ◽  
Euripidis Mistakidis
Keyword(s):  
Wave Structure ◽  
Element Model ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wave Forces ◽  
Intermediate Water ◽  
Wave Loads ◽  
Wave Loading ◽  
Scaled Model ◽  
The Time Domain

The purpose of this work is to examine a three-legged jacket tower support system subjected to wave loading. To this end, linear as well as nonlinear wave scenarios are investigated. The structure was designed for offshore wind turbines installed in intermediate water depths. The phenomenon of the wave-structure interaction is examined experimentally with a 1:18 scaled model as well as numerically with the use of Finite Element Model (FEM). The structural calculations were performed using the structural analysis software SAP2000, which was enhanced by a special programming interface that was developed to calculate the wave loading and to directly apply the wave loads on the structural members. The FEM model in combination with the key parameters that are taken into account, provides a good correlation with the experimental results. The wave theories of Airy and Stokes 5th are employed for the calculation of the wave particle kinematics. The resulting wave forces are examined both in the frequency and in the time domain.

Study of a Hybrid Renewable Energy Platform: W2Power

2018 ◽  
Author(s):  
María J. Legaz ◽  
Daniel Coronil ◽  
Pedro Mayorga ◽  
Javier Fernández
Keyword(s):  
Wave Energy ◽  
Coupled Model ◽  
Offshore Wind ◽  
Offshore Platforms ◽  
Floating Platform ◽  
Control Laws ◽  
Preliminary Study ◽  
Hybrid Renewable Energy ◽  
Fully Coupled ◽  
Made In

The trend in our days seems to drive to hybrid renewable offshore platforms. Several European projects have advanced in this sense. One of these hybrid configurations is obtained by combination of wind and wave energy which allows higher production of electric power. W2Power platform combines offshore wind and wave energy in a semi-submersible floating platform. In this work we present a preliminary study of platform W2Power carried by UCA and collaboration with EnerOcean. A first step of the study, is presented, in this first step the platform and the wave converter are separately studied. A model of these components is created in the software SeaFEM and they are calibrated in the software using previous experimental test tank results. Taking into account this preliminary work, a study of a complete fully coupled model of the W2Power including wind and WECs under different control laws [11] platform will be made in future works.

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