Numerical Study of a Proposed Semi-Submersible Floating Platform with Different Numbers of Offset Columns Based on the DeepCwind Prototype for Improving the Wave-Resistance Ability

Abstract

DeepCwind semi-submersible floating offshore wind turbines have been widely examined, and in some countries this type of floating offshore wind turbine has been adopted in the construction of floating wind farms. However, the DeepCwind semi-submersible floating offshore wind turbines still experience large surge motion that limits their operational time. Therefore, in this study, a semi-submersible floating platform with different numbers of offset columns, but with the same total weight, based on the DeepCwind prototype is proposed. From the free-decay test, it was found that the number of the floating columns will affect the natural frequency of the platform. Furthermore, the regular wave test in the time domain and the irregular wave test in the frequency domain show that increasing the number of the floating columns will reduce the surge motion greatly, while the effects in the heave and pitch motions are not obvious.

Experimental Investigation of the Movement of an Offshore Floating Platform in Straight Wind, Tornadic Wind, and Downburst Conditions

“…The base platform was designed to be a simple, generic floating platform. The design of this model was initially inspired by the DeepCwind tested prototype designs [19,20], then modified to suit materials, test components, and facility size. The geometry represents a simple light duty, multi-purposed platform, which could host many different offshore applications.…”

“…Mathematical models have been developed to examine the dynamic motions of offshore structures in the past [15][16][17]. Additionally, simulations and experimental tests have been completed on offshore structures [18][19][20] however the majority take place in a wave tank or basin and are therefore only able to investigate wave loads. More recently, it has been recognized that it is necessary to consider both wave and wind loads, so recent testing has focused on both parameters.…”

“…The Maritime Research Institute Netherlands (MARIN) Offshore Basin created a 1:50 scaled straight-line only wind generation set-up for model tests concerning wind and wave loading simultaneously [18]. The DeepCwind concept was developed and tested in many stages, and modifications of it were also examined [19][20][21][22]. These experiments involved testing non-optimized floating structure designs to compare the reactions of different generic floating Configurations to wind and wave loads.…”

“…Further, a numerical study was completed to test the Configuration of the floating structure with various numbers of columns [20]. Experimental tests [23] were conducted at the wind-wave-current tank at Newcastle University to test the effect of a stabilizer on the motions of an offshore wind turbine.…”

Floating Offshore Renewable Energy Farms. A Life-Cycle Cost Analysis at Brindisi, Italy

“…At deep water, the supporting structures for wind turbines are floating type, and the main typology are the Semi-Submersible (SS), the Tension Leg Platform (TLP), and the Spar Buoy (SB). Regarding the SS platform, several studies and projects are under development [3][4][5], and a review can be found in Liu et al (2016) [6], while for the TLP typology, most of the projects are still in the scale test phase [7][8][9][10]. Regarding the SB platform, several studies have been carried out in recent years on this typology [11][12][13][14][15] and in October 2017, the world's first floating wind farm, the 30 MW "Hywind Scotland," became operating (https://www.equinor.com).…”