Numerical and Experimental Investigations on the Dynamic Coupling Characteristics of a Novel Semisubmersible Floating-Oscillating-Buoy Wave Energy Converter System

This study develops a semisubmersible floating-oscillating-buoy wave energy converter (WEC), which integrates a semisubmersible platform with a hinged multibuoy cluster, tailored for Chinese offshore regions where wave energy density is approximately one-tenth of European levels. A comprehensive analytical–experimental framework is established to evaluate the coupled dynamic responses and wave power capture of the system under various power take-off (PTO) and arm-length configurations. The model validation is first conducted through the experimental data. Then, the influences of the PTO damping coefficient, PTO elastic coefficient, and actuating arm length on the power capture capability are explored using the analytical model. Ultimately, the optimal wave power absorption is obtained by comparing the root mean square (RMS) values of the extracted power in the PTO system under conditions of different coupling characteristic parameters and different wave frequencies. It is concluded that the power capture capacity of the system can be enhanced by appropriately adjusting the coupling parameters in response to the incident wave frequency. Withc̄= 0.2,k̄= −0.05, andL\ ̄= 1.0 atω= 1.56 rad/s, the optimal RMS capture power can reach 11.7 kW. Significantly, the analytical model is applicable to many hinged multifloating-body type WECs with a hydraulic PTO system, benefiting the optimal design and efficient operation of full-scale WEC prototypes in real sea conditions.