The dependence of offshore turbulence intensity on wind speed

Türk, Matthias; Emeis, Stefan

doi:10.1016/j.jweia.2010.02.005

Cited by 107 publications

(70 citation statements)

References 9 publications

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“…Due to wind direction fluctuations, the given standard deviation of the cup anemometers is not exactly the standard deviation of the horizontal wind speed, though close to it [22]. The scattering of the turbulence intensity depending on wind speed at 90 m height is shown in Figure 3.…”

Section: Turbulence Intensitymentioning

confidence: 82%

“…The objective is to derive the wind field parameters which are necessary for the aeroelastic simulations. An extensive analysis of the wind conditions are given for example in [20][21][22] …”

Section: Analysis Of Fino 1 Measurementsmentioning

confidence: 99%

“…Except of wind speeds lower than 4 m/s, the measured turbulence intensities lie below the IEC C offshore values, and obviously, for all wind speeds they lie below the IEC C onshore values. To get a better matching between the FINO 1 turbulence intensities and the IEC C offshore values, for example [21,22] suggest a modification of Equation 3. Due to wind induced waves, which causes increasing surface roughness, the turbulence intensity increases again for high wind speeds.…”

Section: Turbulence Intensitymentioning

confidence: 99%

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Investigation of Site-Specific Wind Field Parameters and Their Effect on Loads of Offshore Wind Turbines

Ernst

Seume

2012

Energies

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Abstract:The main contributing factors to unsteady loading of Offshore Wind Turbines (OWT) are wind shear, turbulence, and waves. In the present paper, the turbulence intensity and the wind shear exponent are investigated. Using data from the FINO 1 research platform, these parameters are analyzed and compared with the proposed wind field parameters in the IEC standard 61400-3. Based on this analysis, aeroelastic simulations are performed to determine the effect of wind field parameters on the fatigue and the extreme loads on the rotor blades. For the investigations, the aeroelastic model of a 5 MW OWT is used with a focus on design load cases in an operating state (power production). The fatigue loads are examined by means of the damage-equivalent load-range approach. In order to determine the extreme loads with a recurrence period of 50 years, a peak over threshold extrapolation method and a novel method based on average conditional exceedance rates are used. The results show that the requirements of the IEC standard are very conservative for the design of the rotor blades. Therefore, there could be a large optimization potential for the reduction of weight and cost of the rotor blades.

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Section: Turbulence Intensitymentioning

confidence: 82%

Section: Analysis Of Fino 1 Measurementsmentioning

confidence: 99%

Section: Turbulence Intensitymentioning

confidence: 99%

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Investigation of Site-Specific Wind Field Parameters and Their Effect on Loads of Offshore Wind Turbines

Ernst

Seume

2012

Energies

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“…Turbulence intensity is dependent on wind speed (Türk and Emeis, 2010). Wake effects are most pronounced at partial load, and in this range, shear and PO TI are even more related to wind speed.…”

Section: Correlation Analysismentioning

confidence: 96%

An analysis of offshore wind farm SCADA measurements to identify key parameters influencing the magnitude of wake effects

et al. 2017

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Abstract. For offshore wind farms, wake effects are among the largest sources of losses in energy production. At the same time, wake modelling is still associated with very high uncertainties. Therefore current research focusses on improving wake model predictions. It is known that atmospheric conditions, especially atmospheric stability, crucially influence the magnitude of those wake effects. The classification of atmospheric stability is usually based on measurements from met masts, buoys or lidar (light detection and ranging). In offshore conditions these measurements are expensive and scarce. However, every wind farm permanently produces SCADA (supervisory control and data acquisition) measurements. The objective of this study is to establish a classification for the magnitude of wake effects based on SCADA data. This delivers a basis to fit engineering wake models better to the ambient conditions in an offshore wind farm. The method is established with data from two offshore wind farms which each have a met mast nearby. A correlation is established between the stability classification from the met mast and signals within the SCADA data from the wind farm. The significance of these new signals on power production is demonstrated with data from two wind farms with met mast and long-range lidar measurements. Additionally, the method is validated with data from another wind farm without a met mast. The proposed signal consists of a good correlation between the standard deviation of active power divided by the average power of wind turbines in free flow with the ambient turbulence intensity (TI) when the wind turbines were operating in partial load. It allows us to distinguish between conditions with different magnitudes of wake effects. The proposed signal is very sensitive to increased turbulence induced by neighbouring turbines and wind farms, even at a distance of more than 38 rotor diameters.

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“…The TI percentiles at 90 m were extracted from Fig. 2 of Türk and Eimeis (2010) and mapped to the current hub height by scaling with a factor equal to 1.028 according to Next, a shifted Weibull probability density function (PDF) W τ was fitted to the TI for each wind speed. The PDF is defined as…”

Section: Evaluation Of Lifetime Performancementioning

confidence: 99%

Wind inflow observation from load harmonics

Bertelè¹,

Bottasso

Cacciola

et al. 2017

Wind Energ. Sci.

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Abstract. The wind field leaves its fingerprint on the rotor response. This fact can be exploited by using the rotor as a sensor: by looking at the rotor response, in the present case in terms of blade loads, one may infer the wind characteristics. This paper describes a wind state observer that estimates four wind parameters, namely the vertical and horizontal shears and the yaw and upflow misalignment angles, from out-of-plane and in-plane blade bending moments. The resulting observer provides on-rotor wind inflow characteristics that can be exploited for wind turbine and wind farm control. The proposed formulation is evaluated through extensive numerical simulations in turbulent and nonturbulent wind conditions using a high-fidelity aeroservoelastic model of a multi-MW wind turbine.

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The dependence of offshore turbulence intensity on wind speed

Cited by 107 publications

References 9 publications

Investigation of Site-Specific Wind Field Parameters and Their Effect on Loads of Offshore Wind Turbines

Investigation of Site-Specific Wind Field Parameters and Their Effect on Loads of Offshore Wind Turbines

An analysis of offshore wind farm SCADA measurements to identify key parameters influencing the magnitude of wake effects

Wind inflow observation from load harmonics

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