Coupled dynamic analysis of hybrid STLP-WEC offshore floating wind turbine with different mooring configurations

The novel concept of six cone-cylinder-shaped point absorbers around the submerged tension leg platform (STLP) in a circular pattern is studied considering the STLP fixed in position using tensioned mooring cables. The hybrid floating platform consisting of offshore wind turbine platform with a wave energy converter (WEC) reduces the overall logistic cost and eases the transportation process. The stability and safety of the hybrid floating concept depend significantly on the integrity of the tensioned tendons. The present study proposes four different mooring configurations (four, five, eight and nine) to stabilize the hybrid STLP-WEC floater. The numerical simulation in the time domain is performed using the aero-servo-hydro-elastic simulation. The time histories and the motion response spectrums of the surge, sway, heave, roll, pitch and yaw motion of the hybrid system for each mooring configuration are analyzed to study the behaviour of the hybrid system under irregular wave conditions. The time history and spectrum of the generator power are analysed to observe the effect of second-order wave load and turbulent wind loads on the power production of the hybrid floater under each mooring configuration. Further, the study is performed to determine the forces and moments developed at the base of the floating wind turbine to analyze the impact of wind load on the responses of the hybrid floater. The study also analyses the tension developed on each tendon for different mooring configurations and reports the importance of mooring and the influence of the mooring system on the dynamic responses of the combined floater.