Session: 09-01-13 Novel and Hybrid Offshore Wind Concepts

Paper Number: 79432

79432 - Development of 12MW Cross-Shaped Semi-Submersible Floating Offshore Wind Turbine 

We are developing cross-shaped semi-submersible floating structure composed of simple and lean stiffened plate structure. It consists of crossed-box and four sets of footing and column at the tip of the crossed-box structure. While the box and the footing structures are entirely submerged, upper parts of the columns are above the water. The wind turbine is installed on one of the columns.

The feature of this floating structure is that the main column with wind turbine has larger footing structure which means larger volume than others. Since the larger footing structure works as a counterbalance to the heavy weight of the wind turbine, it can realize good balance of load distribution among the whole structure. It means that it is possible to reduce the volume of ballast water and bending moment of the box structure, which prevent an increase in the extra scantling of the box structure, and leads to reduction of steel cost. Moreover, we highly expect the reduction of construction cost and risk of serious damage as there is no small or complex member like brace between each column.

In our paper and presentation, we introduce development study of our 12MW semi-submersible floating offshore wind turbine.

First, we introduce the tank test of our 12MW semi-submersible floating offshore wind turbine, the purpose of which is verifying the behavior under the condition only wave load is applied. As a result of tank test, we verified motion response which is calculated by numerical calculation tool based on potential theory is well reasonable.

Second, we introduce the coupling analysis of our 12MW semi-submersible floating offshore wind turbine. So far, we verified our coupling analysis model from several points of view. We

verified motion response of coupling analysis model under the condition that only wave load is applied. Compared to the result of numerical calculation based on potential theory and tank test, we confirmed motion response of coupling analysis model is valid. We also confirmed the natural frequency of the whole structure and the displacement due to both rigid motion and elastic deformation are reasonable compared to the result of FEM analysis. Now, we are proceeding the coupling analysis under the condition that both wave load and wind load are applied considering the effect of turbine’s operation. After performing the coupling analysis, we will evaluate the structural strength of our 12MW semi-submersible floating offshore wind turbine.

Presenting Author: Ryo Matsuoka Nihon Shipyard

Authors:

Ryo Matsuoka Nihon Shipyard
Takashi Takeda Nihon Shipyard
Hiroki Kusumoto Nihon Shipyard
Shu Kuwada Nihon Shipyard
Haruki Yoshimoto Japan Marine United
Ken Kamizawa Japan Marine United