Mooring system analysis of multiple wave energy converters in a farm configuration

Like all other floating structures, wave energy converters (WECs) need to be kept in position by station-keeping systems in order to realize its functionality and ensure its safety. A compliant mooring system is normally applied and survivability is the main concern for mooring system design. However, WECs based on relative motions impose special requirements on their mooring systems to ensure that they do not affect the energy capture significantly. The purpose of this study is to investigate possible mooring systems for the FO3 WEC which extracts wave energy based on the principle of relative motions between a platform and multiple point absorbers. The study focuses on the survivability of the mooring system for one WEC and for multiple WECs in a farm configuration under extreme environmental conditions. Coupled time-domain simulation of the mooring system for a single WEC is used and compared with the frequency-domain analysis. An integrated mooring system for nine WECs connected by lines is designed and the dynamic behaviour of the whole system in random seas is analyzed by the time-domain method. Based on the analyses of configurations investigated, it is found that the individual mooring is more feasible than the integrated mooring.