A power take-off and control strategy in a test wave energy converter for a moderate wave climate

The energy in the waves of oceans and seas can be converted to electricity by different types of Wave Energy Converters (WECs). Wave energy conversion is currently widely studied to contribute to the world’s rising energy needs. This paper describes a point absorber test WEC that was built for electrical energy production in moderate wave climates as can be found in the Belgian part of the North Sea. A robust design was put forward to assess the feasibility of a full electric rotational Power Take-Off (PTO) system. A stable reactive control algorithm was implemented to optimise the absorbed energy from the waves by tuning the natural frequency of the WEC towards the frequency of the waves. From simulations it is shown that also for real irregular waves, this tuning shows a significant beneficial effect on the absorbed energy. The control parameters for different wave conditions are discussed as well as the effect of the chosen PTO system and its constraints on the absorbed power and optimum control parameters