Concept design and analysis of wind-tracing floating offshore wind turbines

Most of the existing floating offshore wind turbines (FOWT), whether in concept or built, host a single turbine. Structures that can host multiple turbines have received attention in recent years, mainly with the aim of reducing the overall cost of energy production and maintenance. A concept challenge of placing multiple wind turbines on a single floating platform is that under variable wind directions, the leading turbines may block the wind against the trailing turbines. In this work, concept design of a wind-tracing floating structure accommodating three wind turbines is presented. The triangular-shape floating platform is made of pre-stressed concrete, and the turbines are located on the corners. The floating structure uses a single-point mooring system which allows for the entire structure to rotate in response to the change of wind direction. Due to the particular configuration of the floating structure, it is essential to consider the wind, wave and current loads, along with the response of the structure, simultaneously. Response of the FOWT to simultaneous environmental loads from different directions is studied by use of the constant panel approach of the Green function method, subject to constant wind loads on the turbines and linear mooring loads. We also consider the elasticity of the structure by use of finite element analysis, coupled with the hydro- and aero-dynamic loads and responses.