Optimization and evaluation of a semi-submersible wind turbine and oscillating body wave energy converters hybrid system

A hybrid system consisting of a floating offshore wind turbine and wave energy converters (WECs) is promising for multiple extractions of ocean renewable energy. Optimization of the layout and an evaluation of the performance of the hybrid systems are important before practical use but are not well done due to limited simulation tools. This study fills these gaps by proposing a complete toolkit based on the OpenFAST-AQWA framework together with a code that can deal with the full couplings in the problem. A novel DeepCWind-Wave Stars hybrid system is proposed as a representative to validate and practice the new tool. The key parameters of the WECs are optimized using an easily performed method based on the local wave contour disturbed by the platform. Motions, mooring loads, and power of the hybrid system are evaluated under a wide range of wind and wave conditions to examine the influence of the WECs. Results show that the integration of the WECs brings no harm to the stability of the system. The WECs reduce the fluctuation in the mooring force but slightly increase the average mooring force. The generated wave power is an adequate supplement to wind power, especially at a small wind speed.