Power extraction and dynamic response of hybrid semi-submersible yaw-drive flap combination (SYFC)

A combined wind turbine and wave energy converter (WEC) into one unit can harvest more power from marine renewable energy and reduce the cost of energy produced. This paper focuses on the WEC of the semi-submersible yaw-drive flap combination (SYFC) concept and presents the novel hybrid system of flap WEC with a yaw control system to avoid the yaw misalignment of flaps and increase the absorbed power by all WECs. The boundary element method (BEM) is employed to predict the semi-submersible platform hydrodynamics response and flap power under different regular sea state conditions. The validation was first carried out for the response amplitude operator (RAO) and spectral density function (SDF) of the semi-submersible flap combination (SFC) for surge, heave and pitch and line tension in the frequency domain. Afterward, the total absorbed power and capture width ratio (CWR) of the SYFC and SFC at different wave periods and wave heights are presented using the optimum damping coefficient. It is found that the CWR of the SYFC is almost 2-2.5 times more than the CWR of the SFC in almost all wave periods. Finally, the hydrodynamic interaction between the flap and braceless semi-submersible of the SFC and SFYC was presented and discussed.

Automated summary

This paper presents a novel hybrid system combining a wind turbine and wave energy converter (WEC) in order to increase the harvested power from marine renewable energy. The study focuses on the WEC concept of semi-submersible yaw-drive flap combination (SYFC) and introduces a yaw control system to improve power absorption. Using the boundary element method (BEM), the hydrodynamics response and flap power of the semi-submersible platform under different sea state conditions are predicted. The results show that the combined system has a significantly higher capture width ratio (CWR) compared to the individual flap WEC.