The Ocean Grazer is a novel ocean energy collection and storage device that has been proposed by the University of Groningen. Its core technology is a wave energy converter that di ers from others by its adaptability and capacity to store energy. This thesis presents a modular modelling for the Ocean Grazer's power take-o (PTO) system based on the port-Hamiltonian (PH) framework, which enables energy-based analysis and control of the system. The project aims to obtain a reduced model of the PTO system in order to speed up the computation of control signals, which are essential for the optimal operation of the device. The model is developed in the MATLAB/Simulink environment. The rst part of this thesis is dedicated to the modelling of a point-absorber (PA) device, which is the main unit of the PTO system. It is based on a new modelling concept introduced in a previous work, consisting on breaking down the PA into a moving water mass, a buoy-piston ensemble and a pumping hydraulic system. The model is translated into PH framework and simulation results are compared with previously developed models. The second part deals with the modelling of an array point-absorber devices. First, a reference model is presented, acquiring good agreement with validated models. Afterwards, it is described the identi cation of the parameters that de ne the interconnection between the water elements in the present model.