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

Dynamic analysis of multi-wave configurations of a dynamic export cablefor a floating wind turbine in shallow water
Shilun Zhao

Postdoctoral Workstation, China Three Gorges Corporation
Beijing, People’s Republic of China

Yibing Wang

Shanghai Investigation, Design & Research Institute Co., Ltd
Shanghai, People’s Republic of China
Pengfei ChenShanghai Investigation, Design & Research Institute Co., Ltd
Shanghai, People’s Republic of Chinaalgorithms (Poirette, 2017; Rentschler, 2019), and the fatigue
performance of cables (Sobhaniasl, 2020). Nonetheless, these studies aresolely aiming at catenary and lazy wave solutions. The potential multiwave configuration remained to be investigated.

ABSTRACT
To tackle the challenge of applying dynamic export cable in shallow
water, this paper presents a study on the dynamic characteristic andfatigue performance of a dynamic cable with multi-wave configuration
in a semi-sub floating offshore wind turbine (FOWT). The feasibility ofa multi-wave configuration was validated. Through the comparative
study on two hang-off positions on the FOWT, results showed in extreme
sea states the configuration favored a higher hang-off point at the deckbox, while the fatigue estimation revealed a lower position of hang-off
provided superior performance. Finally, suggestions on the design andanalysis of multi-wave cable configuration were given.

The purpose of this study is to study the feasibility and compatibility ofmulti-wave configuration for dynamic export cable applied in shallow
water. For the export cable operating in shallow water, the dynamic andfatigue performance are considered to be significant and essential. Dueto the similarity of the object, the methods applied to umbilical designfrom offshore oil and gas production are also suitable for the dynamic
export cable in FOWT.
This paper is composed of three parts. Firstly, the static of double-wave
configurations is presented and two hang-off locations are selected forfurther analysis. Secondly, the dynamic simulation under survival seastates and transient behavior under turbine fault conditions are performed,respectively. Finally, the fatigue lives of two double-wave cables werecalculated and compared.

KEY WORDS: floating wind; dynamic cable; parametric study;
shallow water; coupled analysis;
INTRODUCTION
In 2021, floating wind technology is stepping into a more commercial
phrase than it is ten years ago. A few more floating demonstrators havebeen installed on-site this year, such as the China Three Gorges (CTG)
Demo (2021), the TetraSpar Demo by Stiesdal (2021), and theDemoSATH by Saitec (2021), etc. Following the increasing demands offloating offshore wind turbine (FOWT) worldwide, dynamic export
power cables are employed in various water depths. To tackle theinevitable challenge of export cable design of FOWT in shallow water,
the multi-wave configuration is considered a useful solution from theexperience of the oil and gas industry (Hanonge, 2010).

THEORETICAL MODEL
Parametric Presentation

The parametric derivation of the 2-wave cable configuration is based on
the catenary equation regardless of the effect of bending stiffness.
Detailed parametric deduction lazy wave and double-wave
configurations can be found in references (Li, 2010; Zhao, 2021),respectively. The general parametric definition of a double-wave
configuration is shown in Fig.1 below.

Field experience on the dynamic export cable coupling to FOWT israther insufficient over the years (Catapult, 2015). However, the limited
relevant studies and researches mainly focus on several aspects, such as
the parametric and sensitivity analysis on hydrostatic performance(Rentschler, 2020; Thies, 2017), the dynamic behaviors induced by theFOWT motions (Thies, 2012), the configuration optimization via various

As presented, the cable comprises five distinct segments. Overall, it canalso be categorized as catenary section and buoyancy section. Specificpoints are noted along the cable from hang-off point A to the touchdown
point (TDP). The vertical distances of B, C, D, E points to sea bed areprescribed.

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