Establishing a Probabilistic Model of Extrapolated Wind Speed Data for Wind Energy Prediction

Wind is among the potential energy resources which can be harnessed to generate wind energy for conversion into electrical power. Due to the variability of wind speed with time and height, it becomes difficult to predict the generated wind energy more optimally. In this paper, an attempt is made to establish a probabilistic model fitting the wind speed data recorded at Makambako site in Tanzania. Wind speeds and direction were respectively measured using anemometer (type AN1) and wind Vane (type WD1) both supplied by Delta-T-Devices at a measurement height of 2 m. Wind speeds were then extrapolated for the height of 10 m using power law equation with an exponent of 0.47. Data were analysed using MINITAB statistical software to show the variability of wind speeds with time and height, and to determine the underlying probability model of the extrapolated wind speed data. The results show that wind speeds at Makambako site vary cyclically over time; and they conform to the Weibull probability distribution. From these results, Weibull probability density function can be used to predict the wind energy.

Authors:

• Mussa I. Mgwatu
• Reuben R. M. Kainkwa

Keywords:

• Probabilistic models
• wind speed
• wind energy

References:

[1] G. Stefan, Prospects for End of the Year 2011, World Wind Energy
Association WWEA, Charles-de-Gaulle-Str. 5, 53113, Bonn, Germany,
2011.
[2] J. Kabadi, "Demand Side Management Program in Tanzania",
Workshop on Global Energy Efficiency, Washington, D.C., 8th March
2010.
[3] Tanzania Electric Supply Company (TANESCO), Generation,
http://www.tanesco.co.tz, retrieved on Monday, 26th March 2012.
[4] A. Benatiallah, L. Kadi and B. Dakyo, "Modelling and Optimisation of
Wind Energy Systems", Jordan Journal of Mechanical and Industrial
Engineering, Vol. 4, No. 1, pp. 143-150, 2011.
[5] H. H. Mwanyika and R. M. Kainkwa, "Determination of the Power Law
Exponent for Southern Highlands of Tanzania", Tanzania Journal of
Science, Vol. 32, No. 1, pp. 103-107, 2006.
[6] C. Nemes, and F. Munteanu, "The Wind Energy System Performance
Overview: Capacity Factor vs. Technical Efficiency", International
Journal of Mathematical Models and Methods in Applied Sciences, Vol.
5, No. 1, pp. 159-166, 2011.
[7] D. -C. Lee and A. G. Abo-Khalil, "Optimal Efficiency Control of
Induction Generators in Wind Energy Conversion Systems using
Support Vector Regression", Journal of Power Electronics, Vol. 8, No.
4, pp. 345-353, 2008.
[8] S. W. Mohod and M. V. Aware, "Laboratory Development of Wind
Turbine Simulator using Variable Speed Induction Motor", International
Journal of Engineering, Science and Technology, Vol. 3, No. 5, pp. 73-
82, 2011.