Modeling and control of a direct drive point absorber for wave energy harvesting

Abstract

Several devices have been developed to convert the wave energy into electricity and they can be found in different degrees of development. A very interesting group of wave energy converters (WEC) is composed of direct drive systems which are characterized by having a simpler mechanical structure compared to others. For example, in the Archimedes Wave Swing (AWS) and the Uppsala/Seabed AB WEC, the Power Take-Off (PTO) system is composed of a linear permanent magnet synchronous generator (PMSG). Due to the nature of the ocean waves, this electricity presents high variability both in amplitude and in frequency. For this reason, direct drive systems require power electronics to convert this very irregular electricity into a form suitable for the grid connection. This work is focused on the WEC modeling in time-domain and, taking advantage of the electronic converter, on maximizing the captured power