Model based feasibility study on bidirectional check valves in wave energy converters

• A simulation model of a discrete fluid power force system is constructed, and implement as a PTO element in a single float Wavestar WEC.
• Bidirectional check valves are found feasible for usage in wave energy converters.
• It is found that the energy production may be slightly improved by utilizing bidirectional check valves rather than on/off valves.
• Only minor additional structural loads are introduced by utilization of bidirectional check valves.

Discrete fluid power force systems have been proposed as the primary stage for Wave Energy Converters (WEC’s) when converting ocean waves into electricity, this to improve the overall efficiency of wave energy devices.This paper presents a model based feasibility study of using bidirectional check valves in wave energy converters to improve the system efficiency. A single float arm of the Wavestar wave energy converter is modelled including the power take-off (PTO) system. The primary stage of the utilised PTO-system is a discrete fluid power force system consisting of a multi-chamber cylinder and multiple common pressure lines. The valve manifold, employed in the discrete PTO system and conventionally equipped with On/Off valves, is instead considered fitted with bidirectional check valves. The energy output from the primary stage is compared for PTO systems occupying respectively On/Off and bidirectional check valves. Based on the analysis it is found that the energy production may be slightly improved by using bidirectional check valves as compared to on/off valves, due to a decrease in switching losses. Furthermore a reduction in high flow peaks are realised. The downside being increased structural loads in the WEC.