Wave prediction and fuzzy logic control of wave energy converters in irregular waves

This paper presents a short comparison of different existing and proposed wave prediction models, which in turn are used to control wave energy converters (WEC) in irregular waves. The objective of the control action is to increase the energy conversion. The prediction models are compared based on the contribution to the prediction of the individual filter weights, in an effort to reduce the filter order. The controller is based on adjusting the short term stiffness and damping of the power take off (PTO) of the WEC. The control action, which is a fuzzy logic (FL) based design, is supported by utilizing nominal damping and stiffness values determined for the given sea state and instantaneous wave using a simple genetic algorithm (GA). The WEC chosen is comprised of a spherical buoy and is modeled using the bond-graph technique. The simulation carried out indicates the proposed algorithm increases the energy conversion of WEC in irregular waves compared to the no control case.