Influence of Unidirectional Power Flow and Restoring Force Absence on Wavepiston Performance

Abstract

Wavepiston is a novel wave energy converter (WEC) comprising multiple energy collectors coupled on a string, each equipped with a sail designed to harness surge excitation from incoming waves. The current configuration features two distinctive design characteristics that significantly influence its hydrodynamic behavior and control: (i) a passive Power Take-Off (PTO) enabling only unidirectional power flow, and (ii) the absence of hydrodynamic restoring capabilities. Despite recent technological progress and a high technology readiness level, limited attention has been given to implementing state-of-the-art control strategies for this device, particularly evaluating how its unique design features influence overall performance. Therefore, this preliminary study aims to evaluate how unidirectional power flow imposed by the passive PTO and the absence of restoring capabilities influence the following performance metrics: (i) power capture across various sea states, (ii) operational spaces of sail stroke and (iii) PTO control force, along with (iv) energy production in a specific wave climate. The results provide a basis for identifying performance trade-offs and support the evaluation of potential design pathways accounting for both device dynamics and wave climate characteristics.