Multi-Objective optimization of an onshore wind tower structure for fatigue and ultimate limit states & dynamics

Abstract

A global awareness about the effect of fossil fuels on the environment has arisen during the last 10 years. As consequence of that, in 2007 the EU set a common target in which 20% of their energy consumption has to be obtained from renewable energies by 2020, by setting particular targets to all Member States. Consequently, there have been huge advances in renewable technologies, especially in the wind sector. Hence, the reduction of CAPEX and OPEX has become an important issue among wind turbine companies in order to make their products more affordable for potential investors. Therefore, it is highly necessary to optimize all components as much as possible. The aim of this MSc project was to optimize the tower structure of an ALSTOM onshore platform called ECO 122 T89. The optimization process was carried out with APOW software which can converge to an optimal solution using different optimization algorithms. More than 3000 tower geometry scenarios were evaluated by calculating their ULS, FLS and dynamics and the results showed a tower raw weight reduction of 2.87%. Then, the industrialization of the two optimal theoretical models was developed in order to use this criterion for choosing the global optimal solution. Furthermore, a sensitivity analysis of the tip clearance effect was carried out and it was observed that the tip clearance effect has an impact of 0.3% in the tower raw weight reduction. This project has been a direct collaboration with the R&D department of ALSTOM and consequently, the results exposed in this MSc thesis are qualitative in order to keep secret the internal values.