Effects of wind speed on wind turbine availability

Modern onshore wind turbines achieve high availabilities of 95-99%. However, these values only give information about the time the wind turbines are in operation and not about the energy they produce compared to their theoretical output. This energy-based availability differs from time-based availability due to the fact that enforced utility downtimes tend to occur during periods of potential high production. To investigate this difference this paper will examine the effect of wind speed dependant failure rates on energy production by analysing turbines subjected to different wind speed time-series to determine the lost energy yield due to wind turbine downtimes.