Comparison of Pre-Construction Energy Yield Assessments and Operating Wind Farm's Energy Yields

摘要

For developers, operators and investors of wind farms it is essential having a most realistic energy assessment including realistic uncertainties before the erection of the farm. A comparison of real operational production data with the pre-construction energy yield assessments has been performed for 235 wind farms globally between 1997 and 2015. Wind farms located in Germany are based on reference energy yields of neighboring wind farms, except of few farms based on wind measurements, international projects are all based on on-site wind measurements. The main objective of this work is identifying existing deviations between post-construction energy yields and pre-construction energy yields and whether given uncertainties reflect the magnitude of real deviations. Additionally different analysis' have been performed for identifying whether changes in assessment procedures, tools and methods led to improvements with regards to energy yields or uncertainties. Possible reasons for deviations are discussed with the aim of lowering these deviations for future assessments. It is shown that the accuracy of the pre-construction assessments could be improved over the years. A significant share of the assessments is hitting the P50 energy yields and given uncertainties generally reflect the magnitude of deviations between pre- and post-construction assessments. Several dependencies could be identified. But still there is some gap between expected energy yields and post-construction energy yields, and a large scatter of the uncertainties.