Modelling and tensioned mooring control of a semi-submersible wind turbine

Our research subject is the 5MW semi-submersible wind turbine model released by the National Renewable Energy Laboratory of the United States. We investigated its motion response and mooring control technology under the combined influence of wind and waves. We have developed seven-degrees-of-freedom multi-rigid-body dynamics models for catenary mooring and tensioned mooring using the Lagrangian method in Matlab. We have also included external wind and wave loading models. The simulation compares the catenary mooring wind turbine model with OpenFast to verify the accuracy of the model. The fuzzy PID control rule is used to control the tensioned mooring wind turbine model by controlling the mooring line retraction and release using the anchor winch fixed on the platform. The research results show that the established wind turbine model is consistent with OpenFast. Under combined wind and wave conditions, the tensioned mooring wind turbine model with mooring control reduces the swing distance and improves stability.