Uncertainty Analysis in Wind Resource Assessment and Wind Energy Production Estimation

This paper presents a mathematical approach to properly account for uncertainty in wind resource assessment and wind energy production estimation. The evaluation of a wind resource and the subsequent estimation of the annual energy production (AEP) is a highly uncertain process. Uncertainty arises at all points in the process, from measuring the wind speed to the uncertainty in a power curve. A proper assessment of uncertainty is critical for judging the feasibility and risk of a potential wind energy development. Many current methods for assessing uncertainty either oversimplify the process or make faulty assumptions, leading to erroneous estimates of uncertainty. The approach in this paper yields a more accurate and objective accounting of uncertainty, and therefore better decision making when assessing a potential wind energy site. Three major aspects of site assessment uncertainty are presented here. First, a method is presented for combining uncertainty that arises in assessing the wind resource. Second, uncertainty in wind turbine power output and energy production is characterized. Third, a method for estimating the overall AEP uncertainty when using a Weibull distribution is presented. While it is commonly assumed that the uncertainty in the wind resource should be scaled by a factor between two and three to yield the uncertainty in the AEP, this work demonstrates that this assumption is an oversimplification, and also presents a closed form solution for the sensitivity factors of the Weibull parameters.