Mathematical Model of a Cogeneration System composed of a Floating Wind Turbine and Two Marine Current Turbines

This paper develops the mathematical model of a cogeneration system composed of a floating wind turbine –type "OC3-Hywind"– and two marine current turbines with the aim of increasing the energy generated by the floating installation and, at the same time, offering the possibility of using those turbines as actuators, being the later useful for the stabilization of the platform in hard weather conditions.The mathematical model for this system has been developed using Matlab. In this tool, several tests have been carried out on the structural stability of the system considering the interactive phase of the acting forces.We have used Matlab to freely design the mechanical system and thus, achieve the desired model, which are a wind turbine type OC3-Hywind and two current turbines.The capacity of Matlab offers the possibility of evaluating the cogeneration system with different geometries, aerodynamic airfoils and external meteorological conditions; and also including or eliminating certain elements, etc. This versatility will be useful in future studies aimed to evaluate this system and maximize the production of energy.In this paper, the first version of the tool is introduced using the "one-dimensional momentum theory" to compute the thrust of the turbines. This theory allows the obtainment of a good approximation to know which will be the behavior that the steady state response system will have. The operational capacity of the tool has been validated by comparing the results with the certificated test of the OC3-Hywind calculated in FAST 8.