Optimisation of Working Areas in Discrete Hydraulic Power Take off-system for Wave Energy Converters

Fluid power is the leading technology in Power Take Off(PTO) systems in Wave Energy Converters(WEC’s), due to the capability of generating high force at low velocity. However, as hydraulic force controlling system may suffer from large energy losses the efficiency of the hydraulic PTO systems may be a limiting factor for wave energy. Therefore, a secondary controlled force system has been proposed as PTO element for WEC’s. This paper investigates the configuration of a multi-chamber cylinder utilising two common pressure lines. By usage of model based optimisation an optimal number and size of working areas is proposed. This area encoding strategy is investigated and compared to two standard binary encodings, finding that the optimised area coding yields significantly higher energy output.