Impact of control strategies on the rating of electric power take off for Wave Energy conversion

In Wave Energy Converters (WECs) the maximum power extraction would be achievable at the expense of a very high rating of the electric and power electronics equipment. The goal of this paper is to show how a convenient trade-off between high power extraction and viable electrical device ratings can be achieved by a proper choice of the WEC control strategy. The case of a direct coupled point absorber in heave is considered, in order to show the impact of the most common control strategies on the power performance. Consequently a revised approach to WEC control is proposed, which is simple and takes into account these potentially conflicting requirements. The targeted application of the presented tool is at the design stage of the power take off, but it also offers a reference-case control principle that can be conveniently adapted to improve the device exploitation when working in real sea conditions. Theoretical analysis and computer simulations are used to show the validity of the proposed approach.