A computational platform for considering the effects of aerodynamic and seismic load combination for utility scale horizontal axis wind turbines

Asareh, Mohammad-Amin; Prowell, Ian; Volz, Jeffery S.; Schonberg, William P.

doi:10.1007/s11803-016-0307-3

Cited by 22 publications

(17 citation statements)

References 7 publications

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“…This guideline suggests that the earthquake and wind loads should be accounted with a factor equal to 0.75. The earthquake loads approximately are represented with a correction factor equal to 1.4 applied to the numerical results of parked condition . The earthquake load demands suggested by GL and AWEA/ASCE are presented in Equations and , respectively:

M_{GL} = M_{Parked} + M_{Aero}

M_{AWEA / ASCE} = 0.75 ((), 1.4 M_{Parked} + M_{Aero})

where M Parked is the tower bending moment demand calculated for parked condition with earthquake excitation and M Aero is the tower bending moment demand evaluated with FAST for turbulent wind field (Figure ) without taking into consideration earthquake loads.…”

Section: Resultsmentioning

confidence: 99%

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Dynamic behavior of wind turbines influenced by aerodynamic damping and earthquake intensity

Yang

Kehua

et al. 2018

Wind Energy

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In the present paper the effects of aerodynamic damping and earthquake loads on the dynamic response of flexible-based wind turbines are studied. A numerical analysis framework (NAF) is developed and applied. NAF is based on a user-compiled module that is developed for the purposes of the present paper and is fully coupled with an open source tool. The accuracy of the developed NAF is validated through comparisons with predictions that are calculated with the use of different numerical analysis methods and tools. The results indicate that the presence of the aerodynamic loads due to the reduction of the maximum displacement of the tower attributed to the dissipation of earthquake excitation energy in fore-aft direction. Emergency shutdown triggered by strong earthquakes results to a rapid change of aerodynamic damping, resulting to short-term instability of the wind turbine. After shutdown of the wind turbine, enhanced dynamic response is observed. For the case where the wind turbine is parked, the maxima displacement and acceleration of tower-top increase linearly with the peak ground acceleration. With the use of the least-square method a dimensionless slope of tower-top displacements is presented representing the seismic response coefficient of tower that can be used to estimate the tower-top acceleration demand. Moreover, on the basis of the seismic response coefficient, an improved model for the evaluation of load design demand is proposed. This model can provide accurate predictions. KEYWORDS aerodynamic damping, dynamic behavior, earthquake intensity, seismic demand, wind turbines | INTRODUCTIONWind energy technology has a leading role in the renewable energy sector. 23.4 GW of new installed capacity of wind turbines that was added in China 1 for 2016; this value corresponds to the 42.8% of the overall added capacity globally for the same year. New installed wind farms are located along the northwest and southeast coasts of China. These wind farms are located in earthquake prone areas, close to the Eurasian and Pacific seismic belts. Wind farms that are located in the aforementioned areas are susceptible to damage on the event of an earthquake.Over the past decades it has been well accepted that earthquakes have a significant effect on the structural dynamic response of wind turbines. 2 Response spectrum method and finite element method (FEM) have been commonly used for the estimation of the seismic load demand of wind turbines. 3 With the use of the response spectrum method the rotor and nacelle are modeled as point lumped masses at tower-top. The seismic load demand of wind turbines can be calculated on the basis of the natural periods, mode shapes, and mass distribution of the tower. 4,5 Usually the aerodynamic damping and higher-order modes are neglected because of the overestimation of the seismic load demand. On the basis of experiments, 6 it is concluded that the seismic excitation increases significantly the lateral displacement of tower-top. On the other hand FEM is applied for the analysis of win...

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M_{GL} = M_{Parked} + M_{Aero}

M_{AWEA / ASCE} = 0.75 ((), 1.4 M_{Parked} + M_{Aero})

Section: Resultsmentioning

confidence: 99%

“…A numerical tool capable for the simulation of the seismic behavior of wind turbines is presented in the literature and is based on FAST tool . The 3 translational degrees of freedom of the foundation were replaced by a linear oscillator.…”

Section: Introductionmentioning

confidence: 99%

Dynamic behavior of wind turbines influenced by aerodynamic damping and earthquake intensity

Yang

Kehua

et al. 2018

Wind Energy

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“…On the basis of the results of the three typical operating scenarios (operational, parked and emergency shutdown), a fragility analysis was performed. Meanwhile, Asareh and Prowell developed a numerical analysis tool named Seismic, for the conduct of seismic analysis of wind turbines using FAST [28][29][30]. In this Seismic tool, a damped actuator was located at the base of the tower in order to replace the degree of freedom (DOF) in translational direction.…”

Section: Introductionmentioning

confidence: 99%

“…The simulation of the coupled OWT foundation models with nonlinear SSI has been noted as major shortcomings of the existing numerical tools [28][29][30]. Therefore, this tool (SAF) makes it possible for the dynamic behaviour of an OWT with flexible or fixed foundations subjected to seismic loadings to be adequately simulated by including the SSI.…”

Section: Introductionmentioning

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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“…25 It is important to note that the nature of the ground in which the WT foundation is placed has a substantial influence on the propagation/attenuation of vibrations from the WT and also in dictating the WT response to aerodynamic loads. 41 For example, soil-…”

Section: Ground Vibrations Induced By Wtsmentioning

confidence: 99%

A new seismic‐based monitoring approach for wind turbines

Barthelmie

Letson

et al. 2018

Wind Energy

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Wind turbine performance and condition monitoring play vital roles in detecting and diagnosing suboptimal performance and guiding operations and maintenance. Here, a new seismic‐based approach to monitoring the health of individual wind turbine components is presented. Transfer functions are developed linking key condition monitoring properties (drivetrain and tower acceleration) to unique, robust, and repeatable seismic signatures. Predictive models for extreme (greater than 99th percentile) drivetrain and tower acceleration based on independent seismic data exhibit higher skill than reference models based on hub‐height wind speed. The seismic models detect extreme drivetrain and tower acceleration with proportions correct of 96% and 93%, hit rates of 91% and 82%, and low false alarm rates of 4% and 6%, respectively. Although new wind turbines incorporate many diagnostic sensors, seismic‐based condition/performance monitoring may be particularly useful in extending the productive lifetime of previous generation wind turbines.

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A computational platform for considering the effects of aerodynamic and seismic load combination for utility scale horizontal axis wind turbines

Cited by 22 publications

References 7 publications

Dynamic behavior of wind turbines influenced by aerodynamic damping and earthquake intensity

Dynamic behavior of wind turbines influenced by aerodynamic damping and earthquake intensity

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

A new seismic‐based monitoring approach for wind turbines

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