Dynamic response analysis of an offshore wind turbine supported by a moored semi-submersible platform
Wind energy, the fastest growing source of renewable energy, is a promising resource for power generation. Offshore wind energy, in particular,offers favorable conditions for power generation—high winds with low turbulence, minimal visual impacts and high generation capacities. Offshore wind turbines mounted on floating platforms are the most economical and viable solution for deep water sites. A semi-submersible platform is an appropriate floating platform for a deep water site, providing stability through high water-plane area. In the wind energy industry, there has been continuing interest in developing larger turbines. At Sandia National Laboratories (SNL), efforts have led to the development of a 13.2 MW wind turbine model with blades 100 meters in length, significantly larger than commercially available blades at present. Such a large wind turbine needs to be carefully analyzed and studied before it can be considered suitable for commercial purposes. The dynamic analysis of the SNL 13.2 MW wind turbine mounted on a moored semi-submersible platform is the subject of this study. This integrated 13.2 MW wind turbine system has been developed and its various physical properties have been studied in this and another associated study. The semi-submersible platform is developed using various modeling tools. For the wind turbine-platform system model developed, dynamic analyses are performed using simulation tools to understand the coupled behavior of the wind turbine and the platform. A reference site is chosen to define the environmental conditions, based on which the short-term extreme response of the offshore wind turbine is estimated. The system is loaded with selected combinations of winds and waves to assess controlling combinations of wind speeds and wave heights that influence the response. The influence of changes in model parameters on overall response is also studied.