Modeling Innovative Power Take-Off Based on Double-Acting Hydraulic Cylinders Array for Wave Energy Conversion

Abstract

Abstract:One of the key systems of a Wave Energy Converter for extraction of wave energy is the Power Take-Off (PTO) device. This device transforms the mechanical energy of a moving body into electrical energy. This paper describes the model of an innovative PTO based on independently activated double-acting hydraulic cylinders array. The model has been developed using a simulation tool, based on a port-based approach to model hydraulics systems. The components and subsystems used in the model have been parameterized as real components and their values experimentally obtained from an existing prototype. In fact, the model takes into account most of the hydraulic losses of each component. The simulations show the flexibility to apply different restraining torques to the input movement depending on the geometrical configuration and the hydraulic cylinders on duty, easily modified by a control law. The combination of these two actions allows suitable flexibility to adapt the device to different sea states whilst optimizing the energy extraction. The model has been validated using a real test bench showing good correlations between simulation and experimental tests. OPEN ACCESSEnergies 2015, 8 2231

Optimal Control of Wave Energy Converters

“…The authors of [117] report that a double-action PTO can supply the output power in each wave period without large instantaneous fluctuating power. A double-acting hydraulic cylinder array is developed in [118], where the model is found to be adaptive to different sea states to achieve higher energy extraction. The authors of [119] present the optimization of a hydraulic PTO of a WEC for an irregular wave where optimal damping is achieved by altering the displacement of the variable-displacement hydraulic motor.…”

Research on Thermodynamic Characteristics of Hydraulic Power Take-Off System in Wave Energy Converter

“…The four check valves integrate the two-way flow of hydraulic oil at the rod-less cavity oil port of the hydraulic cylinders into a one-way flow in the main oil circuit through rectification. The variable displacement hydraulic motor converts the hydraulic energy into rotating mechanical energy, which is then converted into electrical energy output by permanent magnet synchronous generator [3,25].…”

Control of Wave Energy Converters with Discrete Displacement Hydraulic Power Take-Off Units

“…The authors of [15] report that a double-action PTO can supply the output power in each wave period without large instantaneous fluctuating power. A double-acting hydraulic cylinder array is developed in [16], where the model is found to be adaptive to different sea states to achieve higher energy extraction. The authors of [17] present the optimization of a hydraulic PTO of a WEC for an irregular wave where optimal damping is achieved by altering the displacement of the variable-displacement hydraulic motor.…”