ACCURACY OF THE WEATHER RESEARCH AND FORECASTING (WRF) MODEL IN WIND RESOURCE ASSESSMENT : CASE STUDY ABOUT A POTENTIAL REPOWERING SITE

This Master’s thesis studies how accurate the Weather Research and Forecasting (WRF) model is in wind resource assessment in the Nordic conditions. Besides, it is studied how big of an increase in energy production could be gained if a confidential wind farm would be repowered. SCADA data from the existing wind farm is filtered and used to calculate the yearly production of the wind farm. WRF data is used as an input in mesoscale-microscale coupling that results in a yearly production estimation for the same wind farm. When the production results from SCADA and WRF are compared, it is found that the WRF based wind resource assessment overestimates the production with 10 %. This is evaluated to be accurate enough for a preliminary wind resource assessment. This case study confirms that a mesoscale-microscale coupling method where terrain data is combined from two sources leads to acceptable results. It is also shown that the increase of 26 meters in hub height would increase the annual energy production with 8 % and 51 meters height increase would lead to 15 % more production in case of repowering at the studied site. Compared to the existing wind farm, the only parameter changed was the hub height. Therefore, the results of 8% and 15% should be considered only as indicative estimates. The simplicity and apparent accuracy in the wind resource assessment for a repowering project is though questioned in this study