The present paper considers the motion and wave loads on wave energy converters(WEC) connected to large semi-submersible. Twenty-four wave energy converters of heave point-absorbing type are connected to the moored platform. The motions and loads on WECs are measured in the regular and irregular waves as well as the platform motions. The platform motions are compared with the numerical solutions based on the potential flow theory. The measured heave motions of WEC are also compared with numerical solutions based on the Eigenvalue analysis. Additionally, the measured WEC loads with different drafts and different locations are compared each other. Based on these results, characteristics of WECs connected to the large semi-submersible are discussed.


R&Ds on renewable energy is continuing worldwide and interest in ocean energy is increasing. Ocean energy sources have various forms such as wave power, wind power, and tidal power, and research on offshore wind power is being actively conducted. In recent years, there have been emerging structures in which power is generated by a combination of wave power and offshore wind power, which are consistent with the place where power is generated. This type of power generation system has the advantage that it can increase spatial efficiency by combining multiple wave energy converters(WECs) and wind turbines(WTs) into a single structure, and reduce the transportation and installation costs of the mooring system or platform. Poseidon (2015), Wave Treader (2015) and W2-Power (2015) combined power generation structures have been developed in Europe. It is not easy to find the numerical and experimental studies on the hybrid power generation system as the system is under development and research. Recently, a model test results have been presented by Michailides et al. (2016).

An R&D project for a 10 MW class floating wave-offshore wind hybrid power generation system has been also carried out in Korea (Kim et al., 2015b). A semi-submersible platform, which has four vertical columns at each corner of the platform to be connected with horizontal pontoons, was designed for this system considering arrangements of multiple WTs and WECs. A mooring system and power cable were also designed for the position keeping and the electricity transmission.

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