Coupled dynamic analysis of multiple wind turbines on a large single floater

Abstract

The present study has developed a numerical simulation tool for the coupled dynamic analysis of multiple turbines on a single floater (or Multiple Unit Floating Offshore Wind Turbine (MUFOWT)) in the time domain including multiple-turbine aero-blade-tower dynamics and control, mooring dynamics, and platform motions. The numerical tool developed in this study was designed based on and extended from the single-turbine analysis tool FAST to be suitable for multiple turbines. For hydrodynamic loadings of floating platform and mooring-line dynamics, the CHARM3D program developed by the authors was incorporated. Thus, the coupled dynamic behavior of a floating base with multiple turbines and mooring lines can be simulated in the time domain. The developed MUFOWT analysis tool can compute any type of floating platform with multiple horizontal-axis wind turbines (HAWT). To investigate the dynamic coupling effect between platform and each turbine, one turbine failure case with a fully broken blade was simulated and checked. The aerodynamic interference between adjacent turbines, including wake effect, was not considered in this study to more clearly demonstrate only the dynamic coupling. The analysis shows that some damage-induced excitations from one turbine in MUFOWT may induce appreciable changes in the performance of other turbines or the floating platform.