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.