Green Challenge 2014 - Improved Efficiency of Wind Farms by Alternating Mast Heights

Monday 11 Aug 14
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On the 27June, Malene Vested won first price for best master course idea at Grøn Dyst 2014 (Green Challenge).

The project titled 'Improved efficiency of wind farms by alternating mast heights’ dealt with optimisation of wind farms. Since wind turbine wakes are responsible for great energy losses within wind farms, the idea was to reduce wake interaction by the use of two different mast heights.

The idea was tested on a model wind farm in the wind tunnel facility at Portland State University (PSU) by Prof. Raul B. Cal and PhD student Nicholas Hamilton. During Malene Vested's stay at PSU in the summer 2013, she analysed the test measurements and determined the efficiency of the different staggered height wind farm configurations. The analysis showed that the wake interaction is strongly reduced in a staggered height wind farm. In terms of power production, the staggered height model wind farm produced almost as much as a wind farm with only tall masts.

From an economic point of view a combination of tall and standard masts has less construction and maintenance costs compared to tall masts only, thereby reducing the price per kWh. Further studies in e.g. loads are needed and it is expected that the idea must be investigated for real scale wind masts in order to determine whether the laboratory results can be confirmed.

The supervisors on the project were ass. prof. Raul B Cal (Portland State University) and prof. Jens Nørkær Sørensen (DTU).

Further information: M. H. Vested, N. Hamilton, J. N. Sørensen and R. B. Cal Wake interaction and power production of variable height model wind farms, The Science of Making Torque from Wind 2014 (TORQUE 2014)