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Delegates are invited to meet and discuss with the poster presenters during the poster presentation sessions between 10:30-11:30 and 16:00-17:00 on Thursday, 19 November 2015.

Lead Session Chair:
Stephan Barth, ForWind - Center for Wind Energy Research, Germany
Carolin Schmitt juwi Energieprojekte GmbH, Germany
Co-authors:
Carolin Schmitt (1) F Catherine Meissner (2) Jan Borràs Morales (2)
(1) juwi Energieprojekte GmbH, Wörrstadt, Germany (2) WindSim AS, Tønsberg, Norway

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Presenter's biography

Biographies are supplied directly by presenters at EWEA 2015 and are published here unedited

Carolin Schmitt holds a PhD in Meteorology from the University of Karlsruhe. During her professional career she has been involved in various field measurements around the world. Since 2008 her primary working area has been within wind energy. In particular she is responsible for application of new measurement methods as Lidar and new applications for CFD modeling in Site Assessment. Carolin Schmitt is today working as Senior Manager CFD/Lidar for juwi Energieprojekte GmbH.


Poster

Poster Download poster (8.53 MB)

Abstract

Sensitivity of analytical wake models to parameter settings

Introduction

Successful site assessment consists of the correct estimation of wind speed distribution in the park
areas as well as planning an optimized park layout in terms of internal wakes. Even though wind
resource assessment tools might do a good job in describing the wind speed it is still a challenge to
correct the annual energy production (AEP) to take into account wake effects.
Nowadays, challenges come from the combination of growing wind turbines with larger rotor
diameters, more powerful wakes and the requirements of placing as many turbines as possible in
limited planning areas to maximize park output.

Approach

Within this study, the performance of the most common wake models is evaluated in terms of their
sensitivity to different parameter settings and by validation against high resolution production data of a
windpark with changing number of turbines during the years.

Main body of abstract

Several analytical wake models are used in the AEP calculation today and every commercial wind
resource assessment tool has found its own way to implement them. Every wake model has
parameters which can be set either as constant standard values or depending on the surrounding
conditions and those can influence the AEP calculation considerably.
Depending on the individual park situation, the relevant parameters as the wake decay factor, the roughness length at the turbine etc. can be taken from estimated standard conditions or from real
measurement data. Further wake model specific condition as the sub cycles in the wake calculation,
turbulence parameterization and model constants can be chosen.
A commercial CFD tool and the common WAsP model will be used to calculate the change in AEP
when varying those parameters to quantify the sensitivity of the output to different parameters.
The calculated AEP values will be compared to real production to get an idea which parameter
settings might be suitable to describe the AEP as good as possible and which wake model comes
closest to predict the AEP of existing wind farms.

Conclusion

In this presentation we show that even within one wake model, the choice of parameters can have
considerable influence on AEP output and we quantify the results to learn more about the different
analytical wake models and how they are implemented in wind resource assessment tools.


Learning objectives