Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Global Performance Investigation for an 8MW Semi-Submersible Floating Offshore Wind Turbine
SystemXiaohua Shi1, Yongming Cheng2, Yang Shen3, Chunhui Shou3, Fengxing Zhou1, Yinfeng Wang1, Gan Lin1, Guodong He3
1

Zhejiang Zheneng Jiaxing Offshore Wind Energy CO., LtdPinghu, P. R. China
2

3

Beaver Offshore LLCHouston, USA

Zhejiang Energy R&D InstituteHangzhou, P. R. China

presented for the illustration of the regulation facilitated by the bladecontroller. The results include generator power, heave motion, vessel
offset, heel angle, and maximum tension of mooring lines. For the 100yr tropical environmental condition, the wind turbine is parked. The airgap especially at the tip of blades is examined for the extremely parked
case.

ABSTRACTThe offshore wind industry has experienced significant growth inrecent years and continues to expand worldwide. There are a limitednumber of suitable shallow water sites available in offshore locations
for countries currently active in offshore wind. Floating offshore windturbine (FOWT) technologies thus play a leading role in accessing deep
water sites. This paper investigates global performance of an 8MW
semi-submersible floating offshore wind turbine system.

This paper finally summarizes the findings from the global
performance investigation for the 8MW semi-submersible floating
offshore wind turbine system.

The main concepts for offshore wind power are well known in the oiland gas sector, where they are deployed commercially at a large scale.
Platform designs for offshore wind, however, require adaptation toaccommodate different dynamic characteristics and a distinct loading
pattern. Based on reviewing the state-of-art in FOWT, this paper
introduces a new semi-submersible FOWT system developed by theauthors. The system consists of 8MW wind turbine, supporting tower,
semi-submersible platform structure, station keeping mooring lines, anddynamic cable. The principal dimensions of the platform and ballast
setting are designed for the stability and global performance in terms ofresponse amplitude operator (RAO). WAMIT is used to study the RAO
performance. The FOWT system also covers the layout of mooringlines and the configuration of dynamic cable. The semi-submersible
FOWT system is designed to meet the requirement for natural periods
recommended by the guidance notes from ABS.

KEY WORDS: Semi-Submersible; Floating Offshore Wind Turbine(FOWT); Response Amplitude Operator (RAO).

INTRODUCTION
Many countries globally are seeking to rapidly boost their renewable
power capacity as they strive to curb emissions and meet their climatetargets. Offshore wind energy is the deployment of wind farms sited inbodies of water. Higher wind speeds are available offshore compared toon land. As of 2020, the total worldwide offshore wind power capacity
was 35.3 gigawatt (GW). The world installed 6.1 GW of offshore windin 2020, led by China.
The offshore wind industry has the potential to continue to grow,however the foundation of offshore wind turbines currently relies on
fixed monopile foundations, space frame jacket or tripod structures,
which are depth limited to shallow water sites (approximately < 50m).
As the availability of shallow water sites declines, Floating Offshore
Wind Turbine (FOWT) technologies can play a leading role inaccessing deeper water sites and unlocking the full potential of offshore
wind market.

The FEA program of OrcaFlex is used to investigate the time domain
fully coupled aero-hydro-servo-elastic response of the floating windturbine under different environmental conditions. The turbine takes theform of a conventional three-bladed rotor, with variable-speed andvariable blade-pitch control capabilities. The turbine object in OrcaFlexis used to model the generator, gearbox, hub, blades and associatedcontrol systems. The environmental conditions in South China Sea areused in the analysis. The load case matrix covers 1-yr operating, 10-yr,
and 100-yr extreme conditions. The time history of generator power isDriven by the development of renewable energy, the FOWT has beendeveloped quickly over recent years. The ability to install turbines in167