Investigation of the hydraulic response of a spar-type wind turbine for varying wind speed and pitch control

Offshore wind energy has emerged as a significant contributor to renewable energy production. In particular, floating wind turbines have gained attention due to their potential for deep-water deployment, where wind is stronger and more consistent. However, the stability of these structures under varying wind and wave conditions remains a critical concern for their effective deployment and long-term operation. When wind speed exceeds then nominal value, wind turbine adopt a variable pitch control system which mantain the power constant and consequently reduce the thrust force. Whereas, in the wind region below nominal value, the thrust increases proportionally to the square of the wind speed. For floating wind turbine, this behavior leads to positive and negative areodynamic damaping, which according to wind conditions can either stabilize the structure or cause it to depart from the equilibrium point. This study aims to investigate the hydraulic stability of a spar-type wind turbine under varying wind conditions and to evaluate the influence of the negative areodynamic damaping effect on the turbine considered. The Siemens Gamesa wind turbine SG 8.0-167 DD and the structure of the Hywind Tampen's spar turbine are taken as reference technologies. Wind data for the analysis is sourced from the Norwegian Meteorological Institute at the location corresponding to the Hywind Tampen wind farm. The external forces considered in this study include the loads exerted by the wind on the tower and the rotor. The latter is derived using a Blade Element Momentum (BEM) theory approach. By analyzing the platform’s inclination over time and its relative movement, this thesis estimates the power and energy generated over a period of five days.