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Delegates are invited to meet and discuss with the poster presenters in this topic directly after the session 'Wakes: Do we need different models for onshore and offshore wind farms?' taking place on Wednesday, 12 March 2014 at 16:30 -18:00. The meet-the-authors will take place in the poster area.

Angela Hidalgo Global Forecasters SL, Spain
Co-authors:
Angela Hidalgo (1) F P Pedro Angel Jiménez (2) Jorge Navarro (2) Jorge Conte (1) Jesús Fidel González-Rouco (3) Luis Prieto (4)
(1) Global Forecasters SL, Madrid, Spain (2) CIEMAT, Madrid, Spain (3) Universidad Complutense, Madrid, Spain (4) Iberdrola SA, Madrid, Spain

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Abstract

Evaluation of the wind farms impact on the availability of onshore wind resource

Introduction

It is well known that wakes created by wind turbines reduce the wind available at downwind turbines and often represent a large source of energy loss. In order to maximize the profitability of a wind project, it is critical to estimate the power deficit associated with wakes within the wind farm. The problem is aggravated with the presence of nearby wind farms, since these turbines may also affect the wind resource availability a the new site selected for its wind energy exploitation. This second kind of power deficit associated with wakes is still not well understood.


Approach

The target area presents a high density of turbines what allows to analyze how the wind farms energy production can be disturbed by the presence of nearby wind farms. The impact that these wind farms exert upon each other has been investigated using the WRF mesoscale model that allows for the possibility of parameterizing the effects that the wind turbines exert on the atmospheric evolution. The wind farm parameterization (Fitch et al. 2012) has been corrected by the introduction of a perturbation term in the geopotential. This improvement avoids some instabilities effects found when using the parameterization in onshore and offshore areas.

Main body of abstract

A total of 17 wind farms (717 turbines), located in the complex terrain target area, have been included in the present study. The numerical experiment consisted of two WRF simulations with and without representing the effects of the wind turbines. Both simulations span a period of one year using a spatial resolution of 1 km over the target region in order to accurately represent the complexity of the terrain. The vertical resolution was configured to properly take into account the effect of the blades of the ten different turbine classes involved in the experiment. By comparing both simulations, the effects of the wind farms on the availability of wind resource have been estimated. The sensitivity of the impacts of the wind farms to different atmospheric stabilities conditions, such as the corresponding to day or night hours or to the different seasons, has been analysed. The effect of the wind farm on the available wind resource at different regional prevailing wind direction has also been explored.

Conclusion

Results from this modelling experiment indicate that wind power deficits associated with nearby wind farms can be as large as 20 %. Wind farm wakes therefore produce a non-negligible impact in the production of electricity and should be taken into account in the design of a new wind farm over areas with high density of wind turbines.


Learning objectives
1) Investigate the influence that nearby wind farms produce over the wind resource at a given wind farm
2) Explore the potential of mesoscale models to simulate the wind farm wakes.