Dynamic Response Analysis of the Offshore Wind Turbine Support Structure Under Extreme Conditions

2011 ◽  
Author(s):  
Qian Chen ◽  
Shixiao Fu ◽  
Zaojian Zou
Keyword(s):  
Wind Turbine ◽  
Bending Moment ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Response Analysis ◽  
Extreme Conditions ◽  
Wave Load ◽  
Support Structure ◽  
Environmental Loads ◽  
Vortex Induced Vibrations

Based on modal analysis, the environmental loads of an offshore wind turbine under extreme conditions are analyzed, including the static wind load on the support structure, the static current load and wave load on the foundation. The vortex-induced vibrations caused by wind and current have also been studied. The dynamic displacement and bending moment characteristics of the offshore wind turbine support structure under the extreme conditions have been analyzed.

Load Analysis of 2.5MW Offshore Wind Turbine Tower

2011 ◽  
Vol 121-126 ◽  
pp. 206-212
Author(s):  
Cai Yun Ji ◽  
Long Biao Zhu ◽  
Zhi Song Zhu
Keyword(s):  
Wind Turbine ◽  
Offshore Wind ◽  
Irregular Waves ◽  
Offshore Wind Turbine ◽  
Response Analysis ◽  
Linear Wave ◽  
Load Spectrum ◽  
Wave Load ◽  
Wind Turbine Tower ◽  
Load Analysis

With the rapid development of wind power industry and the increasing tension of land resources, WTGS(Wind turbine generating set) changes from Onshore wind machine to offshore wind machine. Because the offshore wind turbine works in the complex environment, it is a higher challenge for tower security. This paper focuses on the load analysis of 2.5MW wind turbine tower, in which a segment solution is applied. Wind load is solved in the superior segment of tower. In the lower segment, the coupling factor of wind and wave is taken into account. Irregular waves are simulated on the basis of the linear wave theory, and then wave load is derived. Accordingly, loads on the tower are calculated by using MATLAB software, and the load spectrum of every node is drawn, which lays a foundation for the dynamic response analysis and fatigue life analysis of tower.

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.

Study on the Dynamic Response for Floating Foundation of Offshore Wind Turbine

2011 ◽  
Author(s):  
Yougang Tang ◽  
Jun Hu ◽  
Liqin Liu
Keyword(s):  
Wind Turbine ◽  
Wind Farm ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wave Load ◽  
Mooring Lines ◽  
Floating Foundation ◽  
Wind Turbine System ◽  
Sea Area

The wind resources for ocean power generation are mostly distributed in sea areas with the distance of 5–50km from coastline, whose water depth are generally over 20m. To improve ocean power output and economic benefit of offshore wind farm, it is necessary to choose floating foundation for offshore wind turbine. According to the basic data of a 600kW wind turbine with a horizontal shaft, the tower, semi-submersible foundation and mooring system are designed in the 60-meter-deep sea area. Precise finite element models of the floating wind turbine system are established, including mooring lines, floating foundation, tower and wind turbine. Dynamic responses for the floating foundation of offshore wind turbine are investigated under wave load in frequency domain.

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.

Individual Blade Pitch Control for Alleviation of Vibratory Loads on Floating Offshore Wind Turbines

2021 ◽  
Author(s):  
Luca Pustina ◽  
Claudio Pasquali ◽  
Jacopo Serafini ◽  
Claudio Lugni ◽  
Massimo Gennaretti
Keyword(s):  
Renewable Energy ◽  
Wind Turbine ◽  
Bending Moment ◽  
Offshore Wind ◽  
Synthesis Process ◽  
Control Synthesis ◽  
Offshore Wind Turbine ◽  
Floating Offshore Wind Turbine ◽  
Blade Root ◽  
Floating Offshore Wind Turbines

Abstract Among the renewable energy technologies, offshore wind energy is expected to provide a significant contribution for the achievement of the European Renewable Energy (RE) targets for the next future. In this framework, the increase of generated power combined with the alleviation of vibratory loads achieved by application of suitable advanced control systems can lead to a beneficial LCOE (Levelized Cost Of Energy) reduction. This paper defines a control strategy for increasing floating offshore wind turbine lifetime through the reduction of vibratory blade and hub loads. To this purpose a Proportional-Integral (PI) controller based on measured blade-root bending moment feedback provides the blade cyclic pitch to be actuated. The proportional and integral gain matrices are determined by an optimization procedure whose objective is the alleviation of the vibratory loads due to a wind distributed linearly on the rotor disc. This control synthesis process relies on a linear, state-space, reduced-order model of the floating offshore wind turbine derived from aero-hydroelastic simulations provided by the open-source tool OpenFAST. In addition to the validation of the proposed controller, the numerical investigation based on OpenFAST predictions examines also the corresponding control effort, influence on platform dynamics and expected blade lifetime extension. The outcomes show that, as a by-product of the alleviation of the vibratory out-of-plane bending moment at the blade root, significant reductions of both cumulative blade lifetime damage and sway and roll platform motion are achieved, as well. The maximum required control power is less than 1% of the generated power.

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