At Sea Experiment of a Hybrid Spar for Floating Offshore Wind Turbine Using 1/10-Scale Model

Abstract

This study aims at development of a cost-effective, floating offshore wind turbine. The prototype model considered herein is composed of (1) 2-MW horizontal-axis wind turbine (HAWT) of downwind type, (2) steel monotower with 55-m hub height above sea level, (3) steel-prestressed concrete (PC) hybrid SPAR-type foundation with 70-m draft, and (4) catenary mooring system using anchor chains. In order to demonstrate the feasibility of the concept, an at-sea experiment using a 1/10-scale model of the prototype has been made. The demonstrative experiment includes (1) construction of the hybrid SPAR foundation using PC and steel, the same as the prototype; (2) dry-towing and installation to the at-sea site at 30-m distance from the quay of the Sasebo shipbuilding yard; (3) generating electric power using a 1 kW HAWT; and (4) removal from the site. During the at-sea experiment, wind speed, wind direction, tidal height, wave height, motion of the SPAR, tension in a mooring chain, and strains in the tower and the SPAR foundation have been measured. Motion of the SPAR has been numerically simulated and compared with the measured values, where basically good agreement is observed.

Experimental Study on Influence of Pitch Motion on the Wake of a Floating Wind Turbine Model

“…Experimental investigations have been done on the structural response of floating support structures by Utsunomiya et al [11]. The equation as posed by Morison, which accounts for inertia and drag force on a body in a flow, was used to determine the wave force on a the spar body and to estimate response amplitudes of a spar bouy.…”

Influence of Floater Response on Wind Turbine Tower Moments in Floating Wind Turbine System

“…Several concepts [ 3,4,5,6,7,8,9,10,11] were proposed for using multiple wind turbines on a single floater. Such floaters have the advantage of using a single mooring and power supply system thus reducing the cost.…”

Flexible dynamic analysis of an offshore wind turbine installed on a floating spar platform

“…where the wave number k and wave angular velocity v are defined as equation (6). Table 3 shows the sea state …”

“…Actually, due to the difficulties in applying the wind and wave loads on the huge floating wind turbine, the real test is hard to be proceeded with full-size model by now. Although the reduced model was tested by real experiment, 6,7 the reduced blades and tower were too short to have flexible deformation that indeed exists in full-size floating wind turbines. One motivation of this article is to reveal the influence of the flexible deformation of the tower and blades on the global motions of the floating wind turbine.…”