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Wake and wind farm modelling

Objective

Improvement, extension and validation of the existing computer codes for wake and wind farm modelling with respect to both power output estimation and design wind load specification.

Development of an improved "modular" wind farm code.

Development of a wake gust model to be used in time-domain structural load calculations for wind farm applications.
Existing wake models have been improved and extended with respect to turbulence, ground effects and wake interference.Results from computational calculations have been compared with measurements. The results look promising.

The combination of the vortex particle model with the kaffa epsilon model is in the final stage.

A concept for the structure of the new modular wind farm code has been made. Basic ideas to define various modules have been outlined. The wake is divided in 3 regions:
the rotor region;
the near wake region;
the far wake region.
The modules consist of functional relations based on the improved wake models and of data bases filled by means of measured results and/or calculated results of the improved wake models. One module describes the turbulence characteristics. It seems that the turbulence intensity in the near wake can be described as a function of the velocity deficit and the undisturbed mean wind speed.

The evaluation of existing gust models has finished. A scheme for a combined gust model using the best parts of the original gust models in order to arrive at a wake gust model has been made.
The project is divided in three parts: coordination, wake and wind farm modelling and gust modelling. In this way a clear distinction can be made among the various activities. Special attention has been paid to a clear definition of the various tasks to be carried out by each participant, including a specification of the input requirements and resultant output of each task. Three project meetings will be held at crucial moments during the project. In these meetings the results of preceding activities will be discussed and succeeding activities will be agreed upon.

Wake and Wind Farm Modelling

In order to arrive at an enhanced wind farm model, able to calculate accurate estimates of the total power output and turbulence properties in wind farms, the underlying flow phenomena will be studied in detail. Advanced wake flow models will be used to investigate the effects relevant to wake flow. Models of different Participants will be combined in order to arrive at a better description of the near and the far wake. Investigation of the development of turbulence in the wake as well as the interaction of multiple wakes. Results of the advanced wake models will be used to develop simplified modules which may be incorporated in the enhanced wind farm model. The wake models and simplified modules will be evaluated and validated using existing experimental data and experimental data made available by the related Joule-Project Full-Scale Measurements on Wind-Turbine Arrays.

Gust Models

Existing gust models will be evaluated. One gust model will be selected to serve as a basis for development of a wake gust model. The possibility to incorporate specific wake characteristics into this latter gust model will be investigated. Wind farm wind statistics will be translated into gust speeds and gust amplitudes typical for the situation in a wind turbine wake to be applied for design wind load calculations of wind turbines. Measured data and analysis results from related JOULE Projects will be used to develop a final wake gust model. In order to tune the activities as much as possible to the specific requirements of future users, representative bodies involved in wind farm development and wind turbine design within Europe will be consulted during the project definition and progress evaluation activities.

Coordinator

Business Unit of TNO Built Environment and Geosciences
Address
Van Mourik Broekmanweg 6
2628 XE Delft
Netherlands

Participants (6)

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE
France
Address
Rue Michel Ange 3
75794 Paris
CENTRE SCIENTIFIQUE ET TECHNIQUE DU BATIMENT - CSTB
France
Address
4, Avenue Du Recteur Poincare
75782 Paris
Centre National de la Recherche Scientifique (CNRS)
France
Address

91406 Orsay
Centre for Renewable Energy Sources
Greece
Address
Km 19Th,marathonos Avenue
19009 Pikermi Attiki
National Power plc
United Kingdom
Address
Kelvin Avenue
KT22 7SE Leatherhead
UNIVERSIDAD POLITECNICA DE MADRID
Spain
Address
Av. Ramiro De Maeztu 7 S/n
28040 Madrid