Effect of PTO on the Dynamics of a WEC-type Floating Breakwater

Zhao, Xuanlie (Dalian University of Technology) | Ning, Dezhi (Dalian University of Technology) | Kang, Haigui (Dalian University of Technology) | Göteman, Malin (Uppsala University)

OnePetro 

Abstract

The hydrodynamic performance of a novel system, which integrates an oscillating buoy wave energy converter with a pile-restrained floating breakwater, is experimentally investigated in a 2-D wave flume. A current controller-magnetic powder brake system is used to simulate the power generation system. Results show that excellent wave attenuation performance and satisfactory capture width ratio of the integrated wave energy system can be achieved at certain ratios between the width of floating breakwater and the wavelength. The wave pressure at the bottom of the breakwater is measured for different values of the excitation current of the current controller, corresponding to the power-take off damping force. The experimental results show that the wave pressure amplitude is affected by the power take-off, and that the installation of a wave energy absorbing system may reduce the horizontal wave loads. Hence, the integration of a wave energy system with the floating breakwater may not only utilize wave energy in a cost-efficient way, but may also improve the breakwater performance and survivability.

Introduction

The first wave energy converter patent was filed in 1799. Since then, various models for absorbing energy from ocean waves have emerged (Lindroth & Leijon, 2011). For many wave energy developers, hunting subsidiaries is a primary task; high construction cost is one of the vital barriers which limits the commercial application of wave energy technology. In terms of engineering applications, cost-sharing is often effective to achieve the goal of cost-reduction of a special technology. In recent years, some concepts for which wave energy converters were integrated into the design of a breakwater have emerged (Arena, Romolo, Malara, & Ascanelli, 2013; Chen, Liu, & Kang, 2015; He & Huang, 2014; Michailides & Angelides, 2012; Margheritini et al., 2009. etc). Here we propose a another configuration, for which the function of cost-sharing between a floating breakwaters and an oscillating wave energy converters can be realized. The boxtype floating breakwater (FB) is vertical pile-restrained, so the FB is restricted to move in heave, and a power take-off (PTO) system was installed above the floating breakwater.