Along with global warming threat, importance of renewable energy development is on the rise for global sustainable development. To amplify productivity of ocean renewable energy, a multi-unit floating offshore wind turbine platform (MUFOWT) is designed by KRISO (Korea Research Institute of Ships and Ocean Engineering). The MUFOWT is a square frame structure with slender bracing structures, and it hosts multiple wind turbines at corners and a series of point absorber-type wave energy converters between the corners. For station keeping, a spread mooring system is employed at each corner. Considering multiple dynamic excitation sources acting on the frame structure such as random waves, mooring tension, wind loads, and wind turbine dynamics, the coupled hydroelastic responses of the MUFOWT are investigated in terms of resonance risk and consequences in motion and structural responses. Using the time-domain hydroelastic analysis tool and time-domain offshore wind turbine dynamics analysis tool developed by the present authors, we investigate global performance of the MUFOWT including the dynamic deformation resulted from the interactions of the floating body dynamics, random sea loads, mooring dynamics and wind turbine dynamics. Moreover, resonance deformation of the MUFOWT and the causes are investigated.
Following aggressive climate changes along with global warming, sustainable development has been on the rise. As one of solutions for zero emission, ocean renewable energy has potential to cover 50% of the U.S. population. For the purpose of commercial ocean renewable energy to connect to the grid, various offshore renewable energy platforms are suggested by the present author (Bae and Kim 2014, Kim and Kim 2016) and KRISO (Kim et al. 2015), which have multiple wind turbines as well as wave energy converters. Particularly, KRISO designed a conceptual offshore renewable energy platform that hosts 4 wind turbines at corners and a series of point-absorber type wave energy converters along each side.