On Study Of Loads And Structural Strength Of The Offshore Floating Wind Turbine

Offshore wind farm from shallow water to deep water is a frontier in the national development of the wind farm, and in the deep water building floating wind farm becomes a new trend. The development of its equipments have succeed in the research related to this technology of Offshore Wind Turbines (OWT) in foreign coutries,while China is just on the threshold in this aspect. The surporting plant, aerodynamic loads, structural strength and hydrodynamic performances of floating vertical-axis wind turbine of 3MW are the important elements which were studied in the paper. The main work of this paper is as following:1. The aerodynamic loads were predicted and the movement law was summarized by stream-tube model theory based on momentum theorem. Then following the design requirements of the wind turbine power, the basic parameters of the wind turbine impeller and the design parameters of work condition, as well as cable length and floating-body structure, were determined.2. Cables, which ensure the vertical turbine work well, is an important part of wind turbine. Parameters, frequency, strength and stiffness of cable directly affect the safety of wind turbine. By the use of relevant theories, cables were designed to meet requirements in the paper. In the process of designing cable, frequency and stress are the two main factors. This text not only calculated frequencies at different intial stress and analized the turbine force under the most dangerous state, cable stiffness also was studied.3. Natural frequencies of wind turbine blades and rotor system were gained by dynamic analysis of structural models, so that resonance vibration can be avoided when wind turbine is working. The key structural strength was calculated in order to make the force and stress in the allowable range. 4. The plantform's hydrodynamic performance of Floating Vertical-Axis Wind Turbine was calculated by Hydrostar, and then the hydrodynamic data was imported to Ariane. Mooring lines were arranged according to the feature of floating-body structure. The entire mooring system was analysed by time-domain analysis, so that Floating Wind Turbine's 6-DOF motion response and mooring lines could satisfy safety requirements.In this paper, the concept of the floating Vertical-Axis wind turbine is proposed and the research on the performace of the system will provide a significant reference value.