Methodology of design of wind turbine tower structures

Abstract

The present work analyzes the methodology of design of wind turbine tower structures considering the dynamical loads obtained using a spectral formulation for the time distribution of wind velocities. The time varying loads thus obtained comprise those due to the wind action on the tower and those due to wind imposed loads on the nacelle and rotor blades. The analysis comprised the calculation of the tower structure response using the shell element and the beam element methodologies. Stress values obtained with the beam element are then compared with values obtained using the shell element model that takes into account the local stress concentrations. Since the basic objective is the global dynamic response of the structure, beam element models provide an efficient and rapid way to obtain the desired dynamic response. Linear dynamical analyses were obtained using a modal superposition technique and compared to a nonlinear analysis obtained using a direct integration technique. Results of dynamical analysis obtained using the beam element model show good agreement with results using the shell element model, enabling a more rapid and efficient methodology to be used in conjunction with the spectral formulation.