Tight-moored amplitude-limited heaving-buoy wave-energy converter with phase control

A time-domain mathematical model has been developed for a tight-moored heaving-buoy wave-energy converter, with a high-pressure hydraulic machinery for energy production and motion control. For comparison, a quite similar hydraulic machinery, without active control, has also been investigated. A procedure is developed for control in irregular waves, and, on the basis of a scatter table, the year-average power production of the buoy with control is estimated to be almost three times that of the buoy without control. Further, a duration curve is presented, which shows that control will give a much smoother power output. The procedure is also reasonably successful in controlling the maximum excursion of the buoy in order to protect the hydraulic machinery. (C) 1998 Elsevier Science Ltd. All rights reserved.