scholarly journals Motion Control of Pentapod Offshore Wind Turbines under Earthquakes by Tuned Mass Damper

2019 ◽  
Vol 7 (7) ◽  
pp. 224 ◽  
Author(s):  
Wenhua Wang ◽  
Xin Li ◽  
Zuxing Pan ◽  
Zhixin Zhao
Keyword(s):  
Seismic Waves ◽  
Passive Control ◽  
Control Method ◽  
Tuned Mass Damper ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Integrated Analysis ◽  
Analysis Model ◽  
Mass Damper ◽  
Structural Responses

The dynamic characteristics of a bottom-fixed offshore wind turbine (OWT) under earthquakes are analyzed by developing an integrated analysis model of the OWT. Further, the influence of the interactions between the rotor and support system on the structural responses of the OWT subjected to an earthquake is discussed. Moreover, a passive control method using a tuned mass damper (TMD) is applied to the OWT to control the responses under earthquakes. The effects of the mass ratio, location and tuned frequency of the TMD on controlling structural responses of the OWT under different recorded seismic waves are studied.

scholarly journals Passive Control of a Pentapod Offshore Wind Turbine Under Earthquakes by Using Tuned Mass Damper

2017 ◽  
Author(s):  
Wenhua Wang ◽  
Zhen Gao ◽  
Xin Li ◽  
Torgeir Moan ◽  
Bin Wang
Keyword(s):  
Wind Turbine ◽  
Seismic Waves ◽  
Passive Control ◽  
Element Model ◽  
Tuned Mass Damper ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Mass Damper ◽  
And Control

The finite element model (FEM) of a pentapod offshore wind turbine (OWT) is established in the newly compiled FAST. The dynamic responses of the OWT are analyzed in detail. Further, a tuned mass damper as a passive control strategy is applied in order to reduce the OWT responses under seismic loads. The influence of the tuned mass damper (TMD) locations, mass and control frequencies on the reduction of OWT responses are investigated. A general configuration of TMD can effectively reduce the local and global responses to some degree, but due to the complexity of characteristics of the OWT structure and seismic waves, the single TMD can not obtain consistent controlling effects.

Study on the Stability of Non-Structural Element Using Active Tuned Mass Damper

2020 ◽  
Vol 17 (7) ◽  
pp. 3224-3230
Author(s):  
Hong-Won Kim ◽  
Dong-Gi Kwag
Keyword(s):  
High Frequency ◽  
Seismic Waves ◽  
Passive Control ◽  
Control Method ◽  
Amplitude Ratio ◽  
Vibration Reduction ◽  
Tuned Mass Damper ◽  
Structural Element ◽  
High Frequency Region ◽  
Mass Damper

Currently, the frequency of earthquakes is increasing in Korea, but due to the lack of appropriate seismic equipment, significant damage is expected. In order to solve this problem, active tuned mass damper will be developed to reduce earthquake damage in response to seismic waves, which are combined from low frequency to high frequency. In this paper, various control methods are introduced to reduce the amplitude ratio occurring at the 1st and 2nd natural frequencies for 3 DOF nonstructural elements. Through mathematical modeling, we confirm how each control method is applied and present the problems of the existing passive tuned mass damper and suggest the active tuned mass damper. To induce an active copper reducer, the response according to the control method can be predicted with a focus on the energy change rate. The active controller receives feedback from the relative displacement and relative velocity of the structure and uses it as a variable to set the control method. The passive control method and the active control method are compared through the simulation, and excellent control performance can be confirmed in the high frequency region as well as the second natural frequency. Vibration reduction performance was confirmed by each control method and the most ideal control method was selected. The optimum vibration reduction performance can be confirmed by using the signal function to always generate 180° of phase difference with respect to the speed of the structure. Not only earthquake but also mechanical vibration, wind load, etc., it can be used in all fields where damage is caused by excitation force inherent in various complex frequencies.

Vibration Control of a Jacket Offshore Wind Turbine Under Earthquake Wind and Wave Loads by Tuned Mass Damper

2020 ◽  
Author(s):  
Xin Li ◽  
Wenhua Wang ◽  
Zuxing Pan ◽  
Bin Wang
Keyword(s):  
Wind Turbine ◽  
Support System ◽  
Passive Control ◽  
Control Method ◽  
Seismic Analysis ◽  
Offshore Wind ◽  
Coupled Analysis ◽  
Offshore Wind Turbine ◽  
Wave Loads ◽  
Structural Responses

Abstract The fully coupled analysis model of a jacket offshore wind turbine (OWT) is established based on the governing equation of motion of the structure which is derived in accordance with the blade element momentum theory (BEM), Morison formula and theories of structural dynamics. The dynamic characteristics and structural responses of the jacket OWT under the different combined seismic cases are analyzed. It can be seen that the interactions of the wind and wave loads are non-negligible in the seismic analysis of an OWT, and the abundant dominant frequencies of the responses of the support system under the combined seismic cases are discovered. Meanwhile, the passive control method of tuned mass dampers (TMD) is applied to the support system of the OWT under the earthquakes, and the influence of the TMD parameters on the reduction of the responses of the support system are investigated. Furthermore, according to the reduction of the structural responses, the suggestions for the design of a TMD under the combined seismic cases for the bottom fixed OWT are summarized.

scholarly journals Evaluation of the Impact of Weather-Related Limitations on the Installation of Offshore Wind Turbine Towers

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3778
Author(s):  
Stephan Oelker ◽  
Aljoscha Sander ◽  
Markus Kreutz ◽  
Abderrahim Ait-Alla ◽  
Michael Freitag
Keyword(s):  
Discrete Event Simulation ◽  
Discrete Event ◽  
Weather Conditions ◽  
Tuned Mass Damper ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Measurement Campaign ◽  
Event Simulation ◽  
Mass Damper ◽  
Wave Heights

Weather conditions have a significant impact on the installation of offshore wind turbines. The rules for installation set clear limits. These limits are usually based on estimations of various experts and not on real assumptions and measurements on-site. When wind speeds and wave heights are too high, work cannot be carried out, and this leads to delays and additional costs. Therefore, we have carried out a measurement campaign during the installation of rotor blades to investigate to which extent the limits can be adjusted by using a tuned mass damper. The results from the measurement campaign—specifically empirically derived significant wave height limits—are used in a discrete event simulation. This study simulates delays resulting from weather conditions. Based on this, the total installation costs are considered. The results of the measurement campaign show that a safe installation with the use of a damper is possible at wave heights of up to 1.6 m. With the discrete event simulation, it is possible to prove that 17.9% can be saved for the costs of the installation vessel. In addition, the wind farm could be erected 32 days faster. Thus, it can be stated that the use of a tuned mass damper simplifies the installation from a technical point of view and is economical.

scholarly journals Application of an Eddy Current-Tuned Mass Damper to Vibration Mitigation of Offshore Wind Turbines

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3319 ◽  
Author(s):  
Jijian Lian ◽  
Yue Zhao ◽  
Chong Lian ◽  
Haijun Wang ◽  
Xiaofeng Dong ◽  
...  
Keyword(s):  
Eddy Current ◽  
Wind Farm ◽  
Permanent Magnets ◽  
Tuned Mass Damper ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Small Scale ◽  
Vibration Mitigation ◽  
Mass Damper ◽  
Extreme Winds

Offshore wind turbine (OWT) structures are highly sensitive to complex ambient excitations, especially extreme winds. To mitigate the vibrations of OWT structures under windstorm or typhoon conditions, a new eddy current with tuned mass damper (EC-TMD) system that combines the advantages of the eddy current damper and the tuned mass damper is proposed to install at the top of them. In the present study, the electromagnetic theory is applied to estimate the damping feature of the eddy current within the EC-TMD system. Then, the effectiveness of the EC-TMD system for vibration mitigation is demonstrated by small-scale tests. Furthermore, the EC-TMD system is used to alleviate structural vibrations of the OWT supported by composite bucket foundations (CBF) under extreme winds at the Xiangshui Wind Farm of China. It is found that the damping of the EC-TMD system can be ideally treated as having linear viscous damping characteristics, which are influenced by the gaps between the permanent magnets and the conductive materials as well as the permanent magnet layouts. Meanwhile, the RMS values of displacements of the OWT structure can be mitigated by 16% to 28%, and the acceleration can also be reduced significantly. Therefore, the excellent vibration-reducing performance of the EC-TMD system is confirmed, which provides meaningful guidance for application in the practical engineering of OWTs.

scholarly journals Active tuned mass damper for damping of offshore wind turbine vibrations

Wind Energy ◽  
2016 ◽  
Vol 20 (5) ◽  
pp. 783-796 ◽  
Author(s):  
Mark L. Brodersen ◽  
Ann-Sofie Bjørke ◽  
Jan Høgsberg
Keyword(s):  
Wind Turbine ◽  
Tuned Mass Damper ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Mass Damper

scholarly journals An Investigation of Passive and Semi-Active Tuned Mass Dampers for a Tension Leg Platform Floating Offshore Wind Turbine in ULS Conditions

2016 ◽  
Author(s):  
Semyung Park ◽  
Matthew A. Lackner ◽  
John Cross-Whiter ◽  
A. Rodriguez Tsouroukdissian ◽  
William La Cava
Keyword(s):  
Wind Turbine ◽  
Active Control ◽  
Wind Turbines ◽  
Structural Control ◽  
Tuned Mass Damper ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Tension Leg Platform ◽  
Tuned Mass Dampers ◽  
Mass Damper

Floating offshore wind turbines are able to access deeper waters with stronger winds, but also have more complicated dynamic behavior than fixed-bottom offshore turbines, potentially resulting in larger loads. Structural control using tuned mass dampers (TMD) is a promising method for mitigating these loads. Previous research on structural control in wind turbines has typically considered passive devices and operational conditions. In this study, the effects of a passive tuned mass damper and a semi-active tuned mass damper, located at the tower top, are analyzed and simulated for the GE Haliade 150–6MW wind turbine located on the Glosten Pelastar tension-leg platform (TLP). The system is simulated using FASTv8, the wind turbine aero-elastic wind turbine simulator developed by NREL, which includes a TMD module capable of modeling passive and semi-active devices. A pendulum-type TMD developed by ESM GmbH, which can oscillate in the fore-aft and side-side directions, is modelled with non-linear position constraints. Semi-active control is defined using an “on-off” TMD damping based on a “ground-hook” control law. Ultimate limit state (ULS) conditions with a parked rotor are simulated, for two different water depths. The results are analyzed in terms of the load reductions at the tower base, nacelle acceleration reduction, and tendon tensions for the various configurations. The impact of TMD stroke limitations and the sensitivity of the results to water depth are investigated. The results will show that structural control can reduce ULS loads in deep water configurations, but are less effective in shallow water. The dynamics of the system that cause this result will be elucidated. The results will also demonstrate that semi-active control can be an effective strategy to further reduce loads and reduce the TMD stroke.

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