Measuring the impact on the turbine lifetime due to the Rotor Blade Extension
After the installation campaign of the Rotor Blade Extension in Penedo Ruivo – Portugal, Energiekontor started to perform an extensive testing campaign which included, among other things:
– Measurement of the overall impact loads on blade root after coupling the RBE
– Measurement of the fatigue loads on the turbine in order to compare its lifetime with the RBE installed
– Measurement of the natural frequency of the tower and blades
– Measurement of the distance between the tower and blade tip
– Blade Mass balancing and Blade Angle deviation campaigns
In order to understand what would be the impact on the turbine lifetime, due to the installation of the RBE, two major tests were performed, i.e. the measurement of the blade root loads and fatigue loads onto the blade.
INEGI, a renowned Portuguese research and technology organisation, performed these campaigns and provided us with the test results.
The scope of this campaign comprised a specifically designed system, which was able to perceive the loads from two turbines, placed right beside each other that have the same wind profile and were erected at the same time. One of these turbines had the RBE installed while the other one did not. The ultimate goal of the analysis was to assess what additional amount of loads is caused by the RBE, by comparing the blade root loads of both wind turbines.
The experimental apparatus, which collected the suffered loads on the blade root, ran for 1 year, in order to obtain all the wind profiling from around the year at the location. All the procedures and calculations were performed, taking into account the IEC 61400-13 standard for all testing campaigns.
The final results from both tests indicated that, according to INEGI’s report, regarding the blade root loads: “The potential load increase induced by the RBE is deemed as negligible as, in fact, such loads are virtually weight derived ones and the increase of weight due to the RBE is practically residual. Even for demanding wind regimes, the increase in wind derived average loads is not expected to exceed 1% in the analyzed blade samples.”
For the fatigue loading campaign the following conclusion was obtained: “The fatigue analysis stresses this conclusion as no obvious trend in strains was found when comparing results from the two turbines, both in number of cycles and strain amplitude.”
Therefore, from the assessment from these campaigns it is not expected that the installation of the RBE will affect the overall turbine lifetime.