Predicting the output power of wind generators is essential to improve grid flexibility, which is vulnerable to power supply variability and uncertainty. Digital twins can help predict the output of a wind turbine using a variety of environmental data generated by real-world systems. This paper dealt with the development of a physics-based output prediction model (P-bOPM) for a 10 MW floating offshore wind turbine (FOWT) for a digital twin. The wind power generator dealt with in this paper was modeled considering the NREL 5 MW standard wind turbine with a semi-submersible structure. A P-bOPM of a 10 MW FOWT for a digital twin was designed and simulated using ANSYS Twin Builder. By connecting the P-bOPM developed for the digital twin implementation with an external sensor through TCP/IP communication, it was possible to calculate the output of the wind turbine using real-time field data. As a result of evaluating the P-bOPM for various marine environments, it showed good accuracy. The digital twin equipped with the P-bOPM, which accurately reflects the variability of the offshore wind farm and can predict the output in real time, will be a great help in improving the flexibility of the power system in the future.

The International Energy Agency Technology Collaboration Programme for Ocean Energy Systems (OES) initiated the OES Wave Energy Conversion Modelling Task, which focused on the verification and validation of numerical models for simulating wave energy converters (WECs). The long-term goal is to assess the accuracy of and establish confidence in the use of numerical models used in design as well as power performance assessment of WECs. To establish this confidence, the authors used different existing computational modelling tools to simulate given tasks to identify uncertainties related to simulation methodologies: (i) linear potential flow methods; (ii) weakly nonlinear Froude–Krylov methods; and (iii) fully nonlinear methods (fully nonlinear potential flow and Navier–Stokes models). This article summarizes the code-to-code task and code-to-experiment task that have been performed so far in this project, with a focus on investigating the impact of different levels of nonlinearities in the numerical models. Two different WECs were studied and simulated. The first was a heaving semi-submerged sphere, where free-decay tests and both regular and irregular wave cases were investigated in a code-to-code comparison. The second case was a heaving float corresponding to a physical model tested in a wave tank. We considered radiation, diffraction, and regular wave cases and compared quantities, such as the WEC motion, power output and hydrodynamic loading.

In this study, a time-domain numerical method based on three-dimensional potential flow was developed to analyze the hydrodynamic characteristics of an inclined oscillating-water-column (OWC) wave energy converter (WEC). A finite element method was applied to solve the potential flow around and inside the OWC chamber. A turbine–chamber interaction was considered to take into account the pressure drop inside the OWC chamber, which is a nonlinear function of airflow speed via turbine operation. The instantaneous pressure drop was updated on the free-surface boundary condition inside the chamber in the time-domain to account for the coupling effect between the turbine and the chamber. The present numerical method was verified by comparing it with the model test results. The hydrodynamic characteristics of an inclined OWC chamber in terms of potential flow, such as the water column motion and the three-dimensional flow distribution around the chamber, were investigated. In terms of hydrodynamic performance, the energy conversion efficiency of the chamber showed a nonlinear response characteristic dependent on the incident wave height. In addition, numerical calculations were carried out to clarify the relationship between the main geometric parameters and the hydrodynamic response of the inclined OWC chamber.