Design of full scale wave simulator for testing Power Take Off systems for wave energy converters

For wave energy to become a major future contributor of renewable energy it is a requirement that the efficiency and reliability of the Power Take-Off (PTO) systems is significantly improved. However, the cost of installing and testing PTO-systems at sea is very high. The focus of the current paper is therefore on the design and commissioning of a full scale wave simulator for testing PTO-systems for point absorbers. The challenge is to be able to design a system, which mimics the behavior of a wave when interacting with a given PTO-system - especially when considering discrete type PTO-systems. The paper presents the designed system, including the major design considerations. A model of the complete system is presented and controllers for the system are developed. These enable the system to emulate the wave behavior and the wave-float interaction. Finally both simulation and experimental results are presented, showing that the system is able to emulate real waves up to three meters in height and with a resulting force of more than 800 kN.