This study is focused on developing a numerical model to evaluate the
performance of a hydraulic PTO system for the TALOS Wave Energy
Converter. The WEC device is described and the architecture of the
hydraulic PTO system is presented with detail. The WEC is modeled
using WEC-Sim, and the PTO is modeled using the Simscape Fluids
library from Simulink. The hydraulic PTO is based on a constant
pressure configuration that is suitable for WEC passive control. The
hydraulic system is composed by a set of rectifying valves and two
hydraulic accumulators that reduce the stiffness of the system and also
serve as energy storage devices. One of the advantages of this hydraulic
PTO architecture is the possibility of controlling the electric generator to
operate around the optimal efficiency operating point. The main
components of the hydraulic PTO are off-the-shelf devices that are
commercially available, which will facility a future deployment of the
designed system. The design variables used for this study are the
accumulator size, the maximum pressure in the accumulators, the
hydraulic motor maximum displacement, and the shaft speed in the
electric generator. The performance of the system is evaluated
individually, using sinusoidal inputs that replicates regular wave
conditions. In addition to this, the numerical model of the PTO is coupled
to a WEC-Sim simulation of the TALOS Wave Energy Converter with
six PTOs to generate a wave-to-wire model. The main objective of this
work is to present a comprehensive design methodology that could serve
as a guideline for future research efforts focused on implementing
control algorithms on multi degree of freedom WECs.