A comparative study on dynamic responses of spar‐type floating horizontal and vertical axis wind turbines

Abstract

Interest in the exploitation of offshore wind resources using floating wind turbines has increased. Commercial development of floating horizontal axis wind turbines (FHAWTs) is emerging due to their commercial success in onshore and near-shore areas. Floating vertical axis wind turbines (FVAWTs) are also promising due to their low installation and maintenance costs. Therefore, a comparative study on the dynamic responses of FHAWTs and FVAWTs is of great interest. In the present study, a FHAWT employing the NREL 5 MW wind turbine and a FVAWT employing a Darrieus rotor, both mounted on the OC3 spar buoy, were considered. An improved control strategy was introduced for FVAWTs to achieve an approximately constant mean generator power for the above rated wind speeds. Fully coupled time domain simulations were carried out using identical, directional aligned and correlated wind and wave conditions. Due to different aerodynamic load characteristics and control strategies, the FVAWT results in larger mean tower base bending moments and mooring line tensions above the rated wind speed. Because significant two-per-revolution (2P) aerodynamic loads act on the FVAWT, the generator power, tower base bending moments and delta line tensions show prominent 2P variation. Consequently the FVAWT suffers from severe fatigue damage at the tower bottom. However, the dynamic performance of the FVAWT could be improved by increasing the number of blades , using helical blades or employing a more advanced control strategy, which requires additional research.

Dynamic Response Analysis of Three Floating Wind Turbine Concepts with a Two-Bladed Darrieus Rotor

“…A semi-submersible type FVAWT with a 5 MW Darrieus rotor mounted on the OC4 DeepCwind semi-submersible (Robertson et al, 2012) was proposed and analyzed by Wang et al (2013). A spar type FVAWT with the same rotor placed on the OC3 Hywind spar buoy (Jonkman, 2010) was also put forward by Borg and Collu (2014) and Cheng et al (2015). Fully coupled aero-hydro-servo-elastic dynamic simulations were carried out for the FVAWTs.…”

Critical Speed Control for a Fixed Blade Variable Speed Wind Turbine

“…The chosen approach also puts the filter cutoff well below the expected natural frequency of the shaft for all operational speeds. Another solution, if higher bandwidth had been required, could have been a notch filter, as suggested in [29].…”

Dynamic Response Analysis of Floating Wind Turbines with Emphasis on Vertical Axis Rotors

“…Comparative study of floating HAWTs and VAWTs was further extended to the spar-type concepts by Cheng et al (2015bCheng et al ( , 2016c. The OC3 spar buoy was used to support the aforementioned two rotors.…”

“…The OC3 spar buoy was used to support the aforementioned two rotors. Cheng et al (2015b) conducted the comparative study using the baseline control strategy for the spar VAWT. To make the comparative study more reasonable, an improved control strategy was employed, as described in Sect.…”