Mitigation of offshore wind turbine responses under wind and wave loading: Considering soil effects and damage

Sun, Cai

doi:10.1002/stc.2117

Cited by 68 publications

(26 citation statements)

References 33 publications

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“…The SSI between monopile and the soil has been modelled using coupled springs placed at the mudline as reported in several recent studies [34][35][39][40][41][42]. A notable shortcoming of this method is that the responses of the embedded pile cannot be obtained correctly.…”

Section: Soil-pile Interaction Modelmentioning

confidence: 99%

Analysis of seismic behaviour of an offshore wind turbine with a flexible foundation

Yang

Bashir

et al. 2019

Ocean Engineering

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Analysis of seismic behaviour of an offshore wind turbine with a flexible foundation http://researchonline.ljmu.ac.uk/id/eprint/10382/ Article LJMU has developed LJMU Research Online for users to access the research output of the University more effectively. , J (2019) Analysis of seismic behaviour of an offshore wind turbine with a flexible foundation. Ocean Engineering, 178. pp. 215-228. Abstract: This paper investigates the effects of nonlinear soil behaviours on the structural responses of offshore wind turbines (OWTs) subjected to wind, wave and earthquake loadings. A novel seismic analysis framework (SAF) is developed for the assessment of seismic behaviours of OWTs with flexible and fixed foundations. The SAF consists of an improved QuakeDyn module that is implemented into an open source tool (FAST). SAF has been validated through benchmark studies using numerical tools and the results show good agreements. Fully coupled nonlinear simulations have been performed for OWTs with fixed and flexible foundations under operational, parked and emergency shutdown states. The flexible foundation is modelled using nonlinear p-y curves obtained using LPILE. For all the examined operating conditions, notable differences of magnitude and variation in the responses between the flexible and fixed cases are observed, indicating the need for soil effects to be accounted in seismic behaviour analysis of wind turbines. It is further observed that the earthquake induces more severe vibrations on wind turbines with a flexible foundation compared to the one with a fixed base. Also, aerodynamic damping dissipates more energy from earthquake excitation resulting in a smaller tower-top fore-aft displacement. The shutdown triggered by the earthquake causes a 34% increase in the mudline bending moment for the flexible foundation case, while a decreasing trend is observed for the fixed foundation model. Similar observations are made  Corresponding author: lichun_usst@163.com 2 / 41regarding the tower-top displacements. The observations imply that ignoring the soil effect may lead to misjudgement of the consequence of an emergency shutdown. The relative orientation of the ground motion with respect to the wind direction causes significant difference in the seismic behaviour of the wind turbine. This confirms that it is necessary to interchange the horizontal components of an earthquake in order to consider the intersectional effect between ground motion and wind.

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Section: Soil-pile Interaction Modelmentioning

confidence: 99%

Analysis of seismic behaviour of an offshore wind turbine with a flexible foundation

Yang

Bashir

et al. 2019

Ocean Engineering

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“…The convective acceleration describes the position-dependent change in the velocity of the liquid stream. a ′ · e t =u t +uu s (6) From Equation 3, by integrating the scalar product g·e t and using the pressure loss Δp as described before in Equation 4, a modified version of the Bernoulli equation can be determined for the S-TLCD as shown in Equation 7, where u is the displacement of the liquid in the tank. ) ds = −2gu − 1 Δp…”

Section: Equation Of Motionmentioning

confidence: 99%

“…In this context, Sun developed for wind turbines subjected to multi-hazards a sophisticated simulation environment, where degradation and soil effects can be simulated. 5,6 He proposed and investigated for monopile offshore wind turbines a semi-active tuned mass damper, which can adapt its damping and frequency parameters. The results show a significant improvement of the control system due to semi-active adaptation capability.…”

Section: Introductionmentioning

confidence: 99%

A semi-active tuned liquid column damper for lateral vibration control of high-rise structures: Theory and experimental verification

Altay

Klinkel

2018

Struct Control Health Monit

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This paper presents a new type of semi-active tuned liquid column damper (S-TLCD) for the lateral vibration control of high-rise civil engineering structures. Analogous to the passive tuned liquid column damper (TLCD), the S-TLCD comprises a U-shaped tank consisting of two vertical columns, which are arranged at a distance from each other and communicating through a horizontal passage. The tank is partially filled with a Newtonian fluid until the liquid reaches a certain level in the columns. In contrast to the passive TLCD, the S-TLCD provides also mechanisms for a continuous adaptation of both its natural frequency and damping behaviour in real time. In the first part of the paper, the governing equations of the S-TLCD are derived on the basis of the Bernoulli equation of a nonstationary incompressible liquid flow. The natural frequency of the S-TLCD is revealed to depend on the scaled length of the liquid. The scaling amount of the liquid length is formulated in dependence of the cross-sectional area ratios of the tank segments. The mathematical description of the S-TLCD is concluded by providing the state-space representation of a multi-degree-of-freedom structure with several S-TLCDs. In the second part of the paper, the derived natural frequency equation is verified, and the proof of concept of the S-TLCD is shown by experimental investigations, which are performed on an S-TLCD model utilizing a test structure and shaking table tests. KEYWORDS adaptive stiffness, adaptive damping, high-rise structures, lateral vibrations, natural frequency tuning, semi-active tuned liquid column dampers Struct Control Health Monit. 2018;25:e2270.wileyonlinelibrary.com/journal/stc

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“…This results in an increase in the efficiency of the system for controlling excessive vibrations. This time-dependent damping algorithm has been used in other works [23,29,32]. In this method, the relative displacement of TMD is tracked in each time step and if it is larger than that of the previous time step, the damping of TMD is set to zero, c d t = 0; otherwise the damping value is set to 2c opt , c d t = 2c opt .…”

Section: Varying Dampingmentioning

confidence: 99%

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

Hemmati

Öterkuş

2018

JMSE

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High flexibility of new offshore wind turbines (OWT) makes them vulnerable since they are subjected to large environmental loadings, wind turbine excitations and seismic loadings. A control system capable of mitigating undesired vibrations with the potential of modifying its structural properties depending on time-variant loadings and damage development can effectively enhance serviceability and fatigue lifetime of turbine systems. In the present paper, a model for offshore wind turbine systems equipped with a semi-active time-variant tuned mass damper is developed considering nonlinear soil–pile interaction phenomenon and time-variant damage conditions. The adaptive concept of this tuned mass damper assumes slow change in its structural properties. Stochastic wind and wave loadings in conjunction with ground motions are applied to the system. Damages to soil and tower caused by earthquake strokes are considered and the semi-active control device is retuned to the instantaneous frequency of the system using short-time Fourier transformation (STFT). The performance of semi-active time-variant vibration control is compared with its passive counterpart in operational and parked conditions. The dynamic responses for a single seismic record and a set of seismic records are presented. The results show that a semi-active mass damper with a mass ratio of 1% performs significantly better than a passive tuned mass damper with a mass ratio of 4%.

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Mitigation of offshore wind turbine responses under wind and wave loading: Considering soil effects and damage

Cited by 68 publications

References 33 publications

Analysis of seismic behaviour of an offshore wind turbine with a flexible foundation

Analysis of seismic behaviour of an offshore wind turbine with a flexible foundation

A semi-active tuned liquid column damper for lateral vibration control of high-rise structures: Theory and experimental verification

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

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