Efficiency Improvement of a Hydraulic Power Take-off of Wave Energy Converter Using Variable Displacement Motor

Wave energy is known to be a promising energy source for the goal of environmental protection and reducing dependence on fossil fuel sources. Hydraulic power-take-off (HPTO) is a key technology of wave energy converters which determines the energy recovery efficiency of the whole system. This paper presents a novel control strategy for HPTO to enhance the regenerated power and energy efficiency by using a suitable configuration of a variable displacement hydraulic motor and a generator. A control management strategy was designed to adjust the tilt angle of the hydraulic motor and the generator resistance load to maintain them working in the highest performance area under variable wave conditions. To verify the proposed system, a simulation model was built in AMESim software based on the previous experiment test bench configuration. Simulation results showed that by applying the proposed strategy, the generated energy increased during the working process. Compared with other control methods, the improvement of energy generation efficiency of the proposed control management method was approximately 10% higher in the low and medium wave conditions.