Capacity factors for wind turbines

Capacity factors in Finland for four wind turbine models, Vestas V90-3.0 MW, V90-2.0 MW, V110-2.0 MW and V136-3.45 MW at four turbine hub heights 100, 125, 150 and 200 m. Wind speed data are from Finnish Wind Atlas [1, 2], from which the Weibull distribution shape and scale parameters (labeled ‘Weibull all data k’ and ‘Weibull all data A’, respectively) and the frequencies of the wind sectors (‘Frequency all data’) were used.

The calculation of capacity factor c_f at wind atlas grid point k is described by the formula
\(c_{\text{f}, k} = \mathop{\mathbb{E}}_{i, s} g(w_i) \approx \sum_{s=1}^{12} f_{k,s} \sum_{i=1}^N p_{k,s}(w_i) g(w_i) \Delta w\),
where g(w) is the power curve function for current wind turbine model, w_i the mean wind speed of bin i, f_k,s the frequency of occurrence of wind direction s at point k, N the number of wind speed bins, p_k,s(w) the Weibull probability density function for sector s at point k at the hub height and Δw the width of the wind speed bin.

References

1. Finnish Meteorological Institute, “Finnish Wind Atlas,” 2008. [Online]. Available: http://www.windatlas.fi. [Accessed: 28-Jun-2016]
2. B. Tammelin, T. Vihma, E. Atlaskin, J. Badger, C. Fortelius, H. Gregow, M. Horttanainen, R. Hyvönen, J. Kilpinen, J. Latikka, K. Ljungberg, N. G. Mortensen, S. Niemelä, K. Ruosteenoja, K. Salonen, I. Suomi, and A. Venäläinen, “Production of the Finnish Wind Atlas,” Wind Energy, vol. 16, no. 1, pp. 19–35, Jan. 2013.