The RBE – Rotor Blade Extension consists of an extension of the blade tip, which increases the area of the turbine rotor and, consequently, energy output.
Considering that the wind turbine generator (WTG) is built to withstand a certain load and a certain functional behaviour, it is necessary to examine its potential effects where modifications occur. In the case of RBE, the extra loads of the extensions placed on the wind turbine blades are all within the parameters defined for its classification according to the International Electrotechnical Commission, and so the lifetime of the modified turbines is not affected. This has been proven as a result of the project calculation and a prototype survey after 3 years of operation, which showed that the status of the gear box and the rotor blade and its extension did not undergo additional wear apart from normal signs of wear and tear.
The following results are obtained from the calculations for a real wind farm:
- 28.4% less revolutions over the turbine lifetime than the number established in the IEC-class I A;
- 0.8% increased 1Hz equivalent load by RBE modification.
In terms of fatigue, the lifetime of the wind turbine is not greatly affected, because it goes through less load cycles than it is designed for.