Wave Excitation Force Estimation for Wave Energy Converters of the Point-Absorber Type

Advanced control strategies play a crucial role in increasing the energy extraction capacity of wave energy converters (WECs). So far, the most promising control schemes have predominantly been studied in simulation, based on the idealized assumption of the wave excitation force availability in real time. In practical WEC implementations, this is not the case, since this force cannot be measured directly when the WECs are running. Hence, the force has to be estimated via the measurement of other quantities. Two approaches are presented in this brief to fulfill this objective. The first approach is based on a Kalman filter coupled with a random-walk model of the wave excitation force, while a receding horizon-unknown input estimation approach-is employed for the second one. The proposed estimation methods are evaluated by using real measurements from a laboratory scale WEC.