Short-time wave force prediction and control strategy for a point-absorber WEC

Abstract

There are several numerical analyses for solving the hydrodynamic responses of a floating body in the time domain. Most of these provide a theoretical solution in the given irregular waves. However, the solution can be obtained only if accurate irregular waves represented by the wave spectrum are provided. Because we consider actual operation, we know that it is difficult to detect accurate irregular waves instantaneously as accuracy is required in most time-domain analyses for the control force feedback to the system. John V. Ringwood proposed a simple control method (SCM) for real-time control of wave energy converter. This paper improves the SCM to predict the practical wave force from the displacement of waves on a floating body in the time domain analysis almost instantaneously. The improved method, that can be applied to predict forces in the wave energy converter with a linear electric generator, helps us to select the control force for the higher conversion of electric power. We examined the control algorithm and confirmed its effectiveness for extensive wave conditions.