Bureau Veritas has completed a Lifetime Extension (LTE) Assessment on an aging wind farm installed in the USA. Ultimately, a three-year LTE was granted and implemented at a fraction of cost of a full repowering. Improvements in maintenance and inspection plans for the wind farm were also achieved. The completion of an LTE Assessment was required by national US regulations in order for the turbine to continue operating beyond its certified Design Life.
When the design lifetime is close to being reached, various options are usually considered: decommission the turbines, repower the site with high rated power turbines or extend the operation of the installed turbines. The latter was the goal of this particular assessment. In this case, the real conditions under which the wind turbine is operating differ from the assumptions made about wind class during the turbine’s design. Through a blend of simulations and a review of the turbine’s Type certification documentation; in particular its corresponding safety margins, the Bureau Veritas team concluded that a Multi-year lifetime extension was feasible. This LTE analysis was conducted using existing turbine performance output, calculations and inspections, and proved that wind farms contain infrastructural components whose design lifetime may be higher than the typical 20+ years design lifetime of wind turbines. To put it simply, replacing a blade or a gearbox will obviously be less expensive than installing an entirely new wind turbine.