Semi-Active Structural Control of Offshore Wind Turbines Considering Damage Development

Hemmati, Arash; Öterkuş, Erkan

doi:10.3390/jmse6030102

Cited by 27 publications

(9 citation statements)

References 40 publications

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“…Thus, it is conventionally required that the extreme response of building structures be restricted within an acceptable level [31,32]. Otherwise, associated measures should be implemented for vibration reduction and control of the dynamic systems [33][34][35][36].…”

Section: Estimation Of Structural Extreme Responsementioning

confidence: 99%

Structural Responses of a Supertall Building Subjected to a Severe Typhoon at Landfall

et al. 2020

Applied Sciences

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Typhoon Mangkhut (1822) was one of the strongest tropical cyclones that ever impacted the south coast of China in past decades. During the passage of this typhoon, the structural health monitoring (SHM) system installed on a 303 m high building in this region worked effectively, and high-quality field measurements at nine height levels of the building were collected successfully, which provides a valuable opportunity to explore the dynamic properties of the building and the associated wind effects. In this study, the typhoon wind characteristics are presented first based on in-situ measurements at two sites. Acceleration responses of the building is then investigated, and the building’s serviceability is assessed against several comfort criteria. This study further focuses on the identification of modal parameters (i.e., natural frequency, damping ratio, and modal shape) via two methods: stochastic subspace identification (SSI) method and a method based on combined use of spectral analysis and random decrement technique (RDT). The good agreement between the two results demonstrates the effectiveness and the accuracy of the adopted methods. The obtained results are further compared with the stipulations in several technical codes as well as simulation results via finite element method to examine their performances in this real case. The amplitude dependence of natural frequencies and damping ratios of the studied building are also stressed.

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Section: Estimation Of Structural Extreme Responsementioning

confidence: 99%

Structural Responses of a Supertall Building Subjected to a Severe Typhoon at Landfall

et al. 2020

Applied Sciences

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“…Sun and Jahangiri [2] designed a three-dimensional pendulum tuned mass damper (3d-PTMD) to control the multi-directional vibration of the OWT, and it has 10% more damping effect than double TMDs have. Hemmati and Oterkus [3] developed a semi-active TMD for the vibration reduction of OWTs; they used a short-time Fourier transform to adjust the damping system to the instantaneous frequency of the system to achieve a better damping effect. The results showed that the performance of a semi-active TMD with a mass ratio (the ratio of mass of TMD to mass of the structure) of 1% is better than a passive TMD with a mass ratio of 4%.…”

Section: Offshore Wind Turbine (Owt)mentioning

confidence: 99%

Multiple TLDs on Motion Reduction Control of the Offshore Wind Turbines

Yeh

Chung

Chen

2020

JMSE

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This study explores the damping effects of tuned liquid dampers (TLDs) on a monopile offshore wind turbine (OWT). The fluid–solid coupling of ANSYS was used to simulate the damping effect of a TLD on the structures. The environmental conditions refer to the IEC-61400-3 and the Design Load Case (DLC) 1.2 for the annual average environmental conditions and DLC 6.2 for the 50-year regression period, and the extreme environmental conditions were used in the study. The turbulent wind field simulation was performed by TurbSim, and the load of wind waves on structures was generated by FAST, which were all developed by the NREL (National Renewable Energy Laboratory). In addition to wind and waves, the seismic force was also considered. The cylindrical TLD was located above the rotor nacelle assembly (RNA). A TLD has different damping effects when acting under wind, wave, and earthquake loads, respectively. The effect of the TLD regarding motion reduction on the OWT under coupled wind, wave, and seismic loads was studied. This study also designed a simple experiment to verify the correctness of the numerical simulation results. Fatigue analysis shows that multi-layer TLDs can extend the fatigue life (37%) of an OWT. In addition, under extreme environmental load conditions, multi-layer TLDs have a better vibration damping performance than single-layer TLDs. The study demonstrates that multi-layer TLDs can be considered as a vibration reduction damper for OWTs.

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“…Also, these controllers are designed to regulate the rotor speed and are not designed for structural vibration/load reduction. Most work on vibration control of wind turbines use external damping devices to reduce unwanted vibrations [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. These studies present various passive, semiactive and active structural control using damping devices.…”

Section: Introductionmentioning

confidence: 99%

Multi-resolution wavelet pitch controller for spar-type floating offshore wind turbines including wave-current interactions

Sarkar

Chen

Fitzgerald

et al. 2020

Journal of Sound and Vibration

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This paper proposes a wavelet multi-resolution based individual pitch control strategy for spar-type floating offshore wind turbines (FOWTs) and investigates its performance under joint wind-wave-current loads considering the effects of wave-current interactions. A multi-resolution analysis (MRA) based wavelet controller that modifies an optimal control problem cast in linear quadratic regulator (LQR) form constrained to a band of frequency has been used in this paper. The weighting matrices of the LQ regulator are varied in different frequency bands depending on the emphasis to be placed on the response energy and control effort to minimize the cost functional of that frequency band. This formulation results in frequency band dependent controller gains that lead to a time-varying controller. Daubechies wavelet is used in the MRA based filter that ensures perfect decomposition of the time signal over a finite interval and fast numerical implementation for control application. The multi-resolution wavelet-LQR individual blade pitch controller is used to control blade out-of-plane vibrations with additional emphasis on 1P frequency of the wind turbine. The emphasis on 1P frequency along with the blade's out-of-plane natural frequency is shown to reduce aerodynamic loads corresponding to 1 st rotational frequency of the wind turbine which in turn reduces vibrations in other modes of the wind turbine. The proposed controller is simulated using a 5-MW baseline offshore wind turbine with realistic operational conditions including wave-current interactions. The controller has been proved to be effective in every analyzed met-ocean condition.

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Semi-Active Structural Control of Offshore Wind Turbines Considering Damage Development

Cited by 27 publications

References 40 publications

Structural Responses of a Supertall Building Subjected to a Severe Typhoon at Landfall

Structural Responses of a Supertall Building Subjected to a Severe Typhoon at Landfall

Multiple TLDs on Motion Reduction Control of the Offshore Wind Turbines

Multi-resolution wavelet pitch controller for spar-type floating offshore wind turbines including wave-current interactions

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