Wave-to-wave buoys control for improved power extraction under electro-mechanical constraints

In order to extract energy from sea waves it is necessary that the motion of Wave Energy Converters (WECs) is properly controlled. This is even more crucial for devices like buoys, whose dimensions are small compared to the wavelength of incident waves. In this paper a control approach which is adapted on a wave-to-wave basis and that employs also a reactive component in addition to the damping one is proposed. This reactive component while improving average power extraction can result in excessive over rating of the Power Take- Off (PTO). On the other hand, the PTO size gives specific limitations on the actual power and torque that the system can handle. The proposed control strategy is developed to optimize the average power extraction by effectively including such electro-mechanical constraints at the algorithm design stage. Simulation tests performed in irregular waves and considering different sea states have shown that such integrated technique leads to a significant improvement of the overall power performance, compared to other, more established, control solutions.