Abstract

The technical challenges in developing PTO systems for wave energy converters are enormous as they have to accommodate both power absorption and survival of extreme waves. The design of PTO systems and their controllers requires complex simulations, taking into account the interaction with the wave energy converter (WEC). However, many of the properties for continuous operation are difficult to reproduce in simulation. PTO and control design for WECs can be facilitated using onshore hardware-in-the-loop (HIL) test-rigs. By performing HIL simulations, it is possible to test the actual PTO and its control equipment under typical operating conditions. To demonstrate the concept we have adapted the scale model of a two degree-of-freedom heaving point-absorber to be tested in this manner. To recreate typical operating conditions, we created and validated a real-time simulation of the WEC, enabling its motion to be emulated using a hydraulic prime mover. The degree of novelty with this work concerns the application of HIL to the above WEC, with real hardware, using an emulated panchromatic sea-state. Experimental results demonstrate the effectiveness of the approach to test a representative PTO system.