Hydrodynamic responses and power efficiency analyses of an oscillating wave surge converter under different simulated PTO strategies

Abstract Experimental investigation on the power performance of a bottom hinged oscillating wave surge converters (OWSC) with different power take-off (PTO) damping strategies (provided by a generic PTO simulation platform) are conducted in regular and irregular waves. The hydrodynamic performance of the OWSC under different damping modes, in regular waves and irregular waves, is observed. For regular waves, the effects of the main influential parameters (including the incident wave height, wave frequency, phase difference between the buoy velocity and wave elevation) on the output power were quantitatively studied. Six damping coefficients of the linear PTO damping is examined under constant incident wave height, and increasing wave frequencies and an output power curve along wave frequency are presented for each input gain of the PTO simulation platform in both linear damping mode and nonlinear damping mode. Additionally, the best coefficient or input gain is obtained for both linear or nonlinear PTO damping mode in different wave conditions. The phase difference between the buoy velocity and wave elevation of the OWSC model in irregular waves has the same trend as that in regular waves. The output electricity in the JONSWAP spectrum is found to be (approximately 300%) higher than that in a user-defined spectrum for the same wave parameters. However, nonlinear PTO strategies have no distinct advantage in the amount of electricity output but have better stability and broader damping range.