Method for controlling a wave-energy-converter system taking into account uncertainties

A method for controlling a wave-energy-converter system that converts energy of sea swells into electrical or hydraulic energy, the wave-energy-converter system comprising at least one movable float linked to a power take-off, and the movable float making an oscillatory movement with respect to the power take-off comprising steps of:

• a) measuring at least one of position, speed and acceleration of the movable float;
• b) estimating the force exerted by the swell on the movable float from the measurement of at least one of position and speed of the movable float;
• c) determining at least one dominant frequency of the force exerted by the swell on the movable float, by an unscented Kalman filter;
• d) determining a control value for the force exerted by the power take-off on the movable float to maximize power generated by the power take-off by:
• i) determining intrinsic resistance for the at least one determined dominant frequency and determining reactance of the movable float, uncertainty intervals of the intrinsic resistance and reactance of the power take-off;
• ii) determining at least one coefficient of a variable-gain control law including a proportional component from a semidefinite-positive optimization of maximization of the power generated by the power take-off, the semidefinite-positive optimization accounting for the intrinsic resistance and reactance of the movable float and the uncertainty intervals of the intrinsic resistance and reactance of the power take-off;
• and
• e) controlling the power take-off with the control value.