Empirical estimation of return period and distribution of duration of wind speed exceedances

Abstract

Wind turbines are designed to function within a certain range of wind speed to optimise production cost and minimise damage limited by technical barriers and usually shut down when wind speed crosses these limits. We present an empirical analysis of extreme events of wind speed outside the functional range of wind turbine and compute the return period of such events using a direct empirical approach. We also demonstrate an extrapolation technique to accurately estimate the return period for time series of short duration. Analysis of wind speed data from various locations reveals that the duration of both upper and lower exceedances can be modelled empirically by the exponential family of distributions very closely. The ideas developed would be useful to wind farm managers for making anticipatory calculations based on past data regarding frequency and durations of wind turbine shut-down due to extreme wind speeds.