Improvements in the Reactive Control and Latching Control Strategies Under Maximum Excursion Constraints Using Short-Time Forecast

Control strategies are essential for the proper functioning of point absorbers. One of them is reactive control, which requires the system to work as a motor during part of the wave cycle and typically places stringent requirements on the efficiency of the power take-off (PTO) machinery. On the other hand, latching control consists of locking the oscillator into position in an intermittent and timely fashion to improve performance over linear damping. This way, the PTO system always works as a generator. This paper proposes latching and reactive control strategies in irregular waves considering short-term predictions on the oscillating system performance. If it is predicted that the end-strokes are going to be reached by the oscillating system, then the damping coefficient will be calculated in order to extract energy so that the velocity vanishes when the end-strokes are reached. The power absorbed by the PTO system significantly increases when the proposed control strategies are applied. Moreover, the oscillating system velocities decrease and the peak-to-average power ratios present acceptable values. The formulation of the proposed methods are presented as well as numerical simulations in regular and irregular waves.