Comparison of linear and cfd models with on-site wind measurement data for wind resource assessment

Abstract

Wind resource assessment (WRA) estimates the strength of wind resources at a planned wind project site. The output of WRA is wind conditions and annual energy production at a wind project site. The aim of this study is to compare on-site measurements with a linear and non-linear flow model results by calculating the error values between and investigating the effects on the annual energy productions. Wind Atlas Analysis and Application Program (WAsP) is used for linear model approach, whilst software called WindSim is used for non-linear model approach based on computational fluid dynamics (CFD) concept. Relative and absolute wind speed errors which have been weighted with the frequency of the directions show that the CFD model gives better results. This non-linear model also leads in annual energy predictions with 1.8% relative error averaged over three met mast results which is 4.2% for linear model. Although non-linear results seem to be better in such a semi-complex site as a further study it is important to run several more test cases for sites with different complexity and stability conditions. The results of non-linear model have been obtained with a new post-processing tool created by Siemens Wind Power. It is also necessary to run the same calculation procedure for several more complex sites before using as a standard tool as this is the first test case of this calculation method.