Numerical calculation and experiment of a heaving-buoy wave energy converter with a latching control

Latching control was applied to a Wave Energy Converter (WEC) buoy with direct linear electric Power Take-Off (PTO) systems oscillating in heave direction in waves. The equation of the motion of the WEC buoy in the time-domain is characterized by the wave exciting, hydrostatic, radiation forces and by several damping forces (PTO, brake, and viscous). By applying numerical schemes, such as the semi-analytical and Newmark B methods, the time series of the heave motion and velocity, and the corresponding extracted power may be obtained. The numerical prediction with the latching control is in accordance with the experimental results from the systematic 1:10-model test in a wave tank at Seoul National University. It was found that the extraction of wave energy may be improved by applying latching control to the WEC, which particularly affects waves longer than the resonant period.