scholarly journals Numerical Modelling of Structures with Uncertainties

2017 ◽  
Vol 24 (s1) ◽  
pp. 125-132 ◽  
Author(s):  
Maciej Kahsin
Keyword(s):  
Sensitivity Analysis ◽  
Modal Analysis ◽  
Complex Structure ◽  
Offshore Wind ◽  
Laboratory Model ◽  
Offshore Wind Turbine ◽  
Surface Model ◽  
Model Parameters ◽  
Fem Model ◽  
Supporting Structure

Abstract The nature of environmental interactions, as well as large dimensions and complex structure of marine offshore objects, make designing, building and operation of these objects a great challenge. This is the reason why a vast majority of investment cases of this type include structural analysis, performed using scaled laboratory models and complemented by extended computer simulations. The present paper focuses on FEM modelling of the offshore wind turbine supporting structure. Then problem is studied using the modal analysis, sensitivity analysis, as well as the design of experiment (DOE) and response surface model (RSM) methods. The results of modal analysis based simulations were used for assessing the quality of the FEM model against the data measured during the experimental modal analysis of the scaled laboratory model for different support conditions. The sensitivity analysis, in turn, has provided opportunities for assessing the effect of individual FEM model parameters on the dynamic response of the examined supporting structure. The DOE and RSM methods allowed to determine the effect of model parameter changes on the supporting structure response.

Monitoring Changes in the Soil and Foundation Characteristics of an Offshore Wind Turbine Using Automated Operational Modal Analysis

2013 ◽  
Vol 569-570 ◽  
pp. 652-659 ◽  
Author(s):  
Gert de Sitter ◽  
Wout Weitjens ◽  
Mahmoud El-Kafafy ◽  
Christof Devriendt
Keyword(s):  
Wind Turbine ◽  
Modal Analysis ◽  
Continuous Monitoring ◽  
Low Frequency ◽  
Operational Modal Analysis ◽  
Human Interaction ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Support Structure ◽  
Lower Natural Frequency

This paper will show the first results of a long term monitoring campaign on an offshore wind turbine in the Belgian North Sea. It will focus on the vibration levels and resonant frequencies of the fundamental modes of the support structure. These parameters will be crucial to minimize O&M costs and to extend the lifetime of offshore wind turbine structures. For monopile foundations for example, scouring and reduction in foundation integrity over time are especially problematic because they reduce the fundamental structural resonance of the support structure, aligning that resonance frequency more closely to the lower frequencies. Since both the broadband wave energy and the rotating frequency of the turbine are contained in this low frequency band, the lower natural frequency can create resonant behavior increasing fatigue damage. Continuous monitoring of the effect of scour on the dynamics of the wind turbine will help to optimize the maintenance activities on the scour protection system. To allow a proper continuous monitoring during operation, reliable state-of-the-art operational modal analysis techniques should be used and these are presented in this paper. The methods are also automated, so that no human-interaction is required and the system can track the natural frequencies and damping ratios in a reliable manner.

Decommissioning of Offshore Monopiles, Occuring Problems and Alternative Solutions

2018 ◽  
Author(s):  
Nils Hinzmann ◽  
Philipp Stein ◽  
Jörg Gattermann
Keyword(s):  
Wind Farm ◽  
Complex Structure ◽  
Complete Removal ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Offshore Wind Farm ◽  
Narrow View ◽  
Alternative Solutions ◽  
German Offshore Wind Industry ◽  
Offshore Wind Industry

The German offshore wind industry has historically grown since the first offshore wind farm (OWF) “alpha ventus” was completed in 2010. Since the end of 2017 a total number of 18 OWF with a capacity of about 5 GW have been operating in the German Exclusive Economic Zone (EEZ) [1]. While the majority of the population and the industry focus on new projects, it appears the life cycle observation and especially the decommissioning phase remain largely unattended. This narrow view can lead to unexpected and expensive consequences in the future. The decommissioning of a complex structure as an offshore wind turbine (OWT) needs to be planned well in advance. There are numerous aspects that make the decommissioning a challenge, such as the federal regulations, the marine environment and the technical limitations of offshore operations. This article gives an overview of the problematic matter of dealing with monopiles after the predicted lifetime, the geotechnical condition, analyses of the current decommissioning options and identification of issues in regards to the decommissioning method. Furthermore, other promising decommissioning methods for a complete removal of offshore monopiles, such as vibratory extraction, internal dredging, external jet drilling and the use of buoyancy force, are presented and compared concerning a possible combination. Some of the presented methods are highly experimental, others are commonly used in other industries.

scholarly journals Modal analysis for optimal design of offshore wind turbine blades

2020 ◽  
Vol 30 ◽  
pp. 998-1004
Author(s):  
Hicham Boudounit ◽  
Mostapha Tarfaoui ◽  
Dennoun Saifaoui
Keyword(s):  
Optimal Design ◽  
Wind Turbine ◽  
Modal Analysis ◽  
Turbine Blades ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wind Turbine Blades

scholarly journals Digital twin modeling for predictive maintenance of gearboxes in floating offshore wind turbine drivetrains

2021 ◽  
Author(s):  
Farid K. Moghadam ◽  
Geraldo F. de S. Rebouças ◽  
Amir R. Nejad
Keyword(s):  
Dynamic Properties ◽  
Model Identification ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Model Parameters ◽  
Test Case ◽  
Digital Twin ◽  
Twin Model ◽  
Control And Monitoring System ◽  
Useful Lifetime

AbstractThis paper presents a multi-degree of freedom torsional model of drivetrain system as the digital twin model for monitoring the remaining useful lifetime of the drivetrain components. An algorithm is proposed for the model identification, which receives the torsional response and estimated values of rotor and generator torques, and calculates the drivetrain dynamic properties, e.g. eigenvalues, and torsional model parameters. The applications of this model in prediction of gearbox remaining useful lifetime is discussed. The proposed method is computationally fast, and can be implemented by integrating with the current turbine control and monitoring system without a need for a new system and sensors installation. A test case, using 5 MW reference drivetrain, has been demonstrated.

The Marine Environment Impacts on the Supporting Structure of the Offshore Wind Turbines and Discussions on the Protective Measures

2014 ◽  
Vol 1065-1069 ◽  
pp. 1381-1389
Author(s):  
Yong Xiang Wu ◽  
Hong You Li ◽  
Hong Ming Chi ◽  
Li Yuan Liu ◽  
An Min Cai ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Marine Environment ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Protective Measures ◽  
Offshore Wind Turbines ◽  
Supporting Structure ◽  
Seawater Corrosion ◽  
Negative Factors

Offshore wind turbine supporting structure long term works in the harsh marine environment, suffering from a variety of negative factors such as the seawater corrosion, marine growths, water scour, collision of sea ice and ship, etc.. Through numerical analysis software SACS and ANSYS, the marine environment impacts on the supporting structure and protective measures were put forward. The study found that such adverse environmental factors might easily result in a whole or partial component damage of the foundation support structure, and eventually lead to the reduction of security and durability. Reasonable preventive measures to ensure the security of the offshore wind turbine supporting structure were proposed and theoretical guidance for the design of future offshore foundation was provided.

Sign in / Sign up

Export Citation Format

Share Document