Round Robin Laboratory Testing of a Scaled 10 MW Floating Horizontal Axis Wind Turbine

Abstract

This paper documents the round robin testing campaign carried out on a floating wind turbine as part of the EU H2020 MaRINET2 project. A 1/60th scale model of a 10 MW floating platform was tested in wave basins in four different locations around Europe. The tests carried out in each facility included decay tests, tests in regular and irregular waves with and without wind thrust, and tests to characterise the mooring system as well as the model itself. For the tests in wind, only the thrust of the turbine was considered and it was fixed to pre-selected levels. Hence, this work focuses on the hydrodynamic responses of a semi-submersible floating foundation. It was found that the global surge stiffness was comparable across facilities, except in one case where different azimuth angles were used for the mooring lines. Heave and pitch had the same stiffness coefficient and periods for all basins. Response Amplitude Operators (RAOs) were used to compare the responses in waves from all facilities. The shape of the motion RAOs were globally similar for all basins except around some particular frequencies. As the results were non-linear around the resonance and cancellation frequencies, the differences between facilities were magnified at these frequencies. Surge motions were significantly impacted by reflections leading to large differences in these RAOs between all basins.

A Heuristic Approach for Inter-Facility Comparison of Results from Round Robin Testing of a Floating Wind Turbine in Irregular Waves

“…The round robin test plan was developed by Ifremer and included hydrostatic tests, mooring stiffness checks, decay tests in calm water (with and without moorings), test in regular waves without wind thrust, and tests in irregular waves with wind thrust. A full description of the model and the test campaign is presented by [7]. For the remainder of this paper, the five datasets obtained from the four test facilities are referred to as A, B, C, D, and E in accordance with Table 1 and to ensure consistency with [7].…”

“…A full description of the model and the test campaign is presented by [7]. For the remainder of this paper, the five datasets obtained from the four test facilities are referred to as A, B, C, D, and E in accordance with Table 1 and to ensure consistency with [7].…”

“…The responses to waves have been analysed and reported in [7], in which Response Amplitude Operators (RAOs) were used. The shape of the motion RAOs were globally similar for all basins except around some particular frequencies.…”

“…To investigate the effect of the facility, a round robin testing program was executed in MaRINET2 whereby generic wave, floating wind, and tidal devices were tested in different infrastructures. The wave [4][5][6] and wind [7] round robin testing included many tests in waves. One of main lessons learnt from this exercise is that it is not straightforward to compare results of wave tests obtained from different basins.…”

“…One of main lessons learnt from this exercise is that it is not straightforward to compare results of wave tests obtained from different basins. Linear response amplitude operators (RAOs) were found valuable for a first comparison [7]. However, the impossibility of generating identical waves in two distinct basins combined with the fact that responses to waves are not fully linear bring an additional challenge for a cross-facility comparison.…”