Session: 09-01-01: Offshore Wind Energy - Installation

Paper Number: 101206

101206 - Comparative Study for Numerical Modelling and Analysis of Floating Offshore Wind Onsite Installation 

As the global demand for floating offshore wind power grows, research and development of installation methods continue. The existing floating offshore wind power installation method involves mating wind towers and floaters at a quayside and towing the mated units to an operation site. As the size of wind towers is expected to increase and wind parks will be located further from the shore in future, the conventional method is considered unattractive due to the long towing time. This paper discusses one of the proposed alternative installation methods, an onsite installation method of directly installing wind turbines at the operation site. Since fully assembled wind turbines are lifted and mated to the floating spar substructures on the operation site, complex responses are expected from the complex multi-body system of the installation vessel, floater and lifted wind turbine. An initial feasibility study was performed for this alternative installation method with numerical modelling and dynamic analyses. The obtained results may provide a basis for understanding the complex system responses under environmental loads and may be used to design system components such as installation vessels, floaters, mooring, fender and control systems. In order to validate numerical models and analysis results, related experiments should be accompanied. However, it requires multiple iterations during the initial design phase and has inherent limitations in implementing complex multi-body systems into experiments. Therefore, it is common to adopt numerical modelling and analysis results that are advantageous in terms of time and cost compared to prototyping and experiments. In this study, the alternative installation system was modelled using Sima and Orcaflex, and the numerical analysis results were compared. Although Sima and Orcaflex are the most used and proven tools for analysing marine operations in academia and industry, they have differences in numerical methods, implementation of related theories, module fidelity, and built-in settings for modelling and analysing complex systems. Therefore, the comparative study on numerical modelling and analysis results for the alternative installation methods of floating offshore wind power is meaningful. The comparative study was carried out in the following steps: 1) eigenvalue analysis of the installation system; 2) time-domain analyses of the installation system without the fender system between the vessel and floater; and 3) time-domain analyses with the fender system. This study will verify the reliability of the analysis results of the proposed installation method, increase the understanding of system dynamics, and provide a basis for design optimisation of the installation system.

Presenting Author: Sunghun Hong Norwegian University of Science and Technology

Presenting Author Biography: Sunghun Hong is a PhD research fellow at Norwegian University of Science and Technology, researching and developing alternative installation methods for floating offshore wind energy. He is also a Senior Engineer at the Wood Group, responsible for floating offshore wind research, installation analysis, offshore platform repair design, and project development and proposal preparation. He focuses on expanding the competencies of engineering consultants in offshore wind energy and SURF (Subsea Umbilicals, Risers and Flowlines) technologies. His project engineering and management experience includes Floating Offshore Wind and SURF Engineering Phases (Tender Proposal, Concept Study, Pre-FEED, FEED and Detailed Design), Shipbuilding, Quality Assurance and Multi-discipline EPCI delivery.

Authors:

Sunghun Hong Norwegian University of Science and Technology
Shuai Yuan Norwegian University of Science and Technology
Houxiang Zhang Norwegian University of Science and Technology
Karl Henning Halse Norwegian University of Science and Technology