Wind turbine availability analysis based on statistical data

Availability is an important performance index for wind turbines. To predict wind turbine availability, failure rate and repair rate have to be known. There are some sources of wind turbine failure data that can be used to estimate parameters of the failure rate function and the repair rate. With repair rate assumed to be constant, this paper first presents maximum likelihood estimates for failure rate, then gives a method to predict instantaneous and long term availability for wind turbines. By keeping a record of failure time for each subassembly of a wind turbine, maintenance could be more effectively targeted with more detail in terms of what is likely to fail. Failure data from a wind farm is analyzed as an example, which shows results predicted by the technique presented are close to the wind farm statistics. This work will be helpful in planning timely and cost-effective maintenance of wind turbines.