Integration of a semisubmersible floating wind turbine and wave energy converters: an experimental study on motion reduction

2019 ◽  
Vol 25 (3) ◽  
pp. 667-674
Author(s):  
Hongzhong Zhu ◽  
Changhong Hu ◽  
Makoto Sueyoshi ◽  
Shigeo Yoshida
Author(s):  
Zheng Chen ◽  
Weijian Zeng ◽  
Ming Tan ◽  
Dahai Zhang ◽  
Yulin Si

Abstract Recent years have seen rapid development in offshore wind technology. Particularly, floating offshore wind turbines possess great potential in deep water coastal places around the world, though they are now still in the demonstration phase. At the same time, the unused wave energy is also abundant at the sites of offshore wind farms, especially those in deep sea regions. Collecting wave energy in offshore wind farms might benefit both total energy production and reduce maintenance cost. Therefore, integrating offshore wind turbine with wave energy conversion devices could be a good idea to achieve higher efficiency and lower cost. In this paper, we report a combined wind and wave energy power generation concept called WindOWC, which constits of a 5MW wind turbine and three oscillating-water-column (OWC) wave energy converters (WECs). The wind turbine is mounted on a semi-submersible floating platform, which is similar to OC4-semibsubmersible, and the OWCs are located in its three offset columns. In this design, the wind turbine and WECs share the same supporting platform and the power transmission system, thus is expected to reduce the cost of energy. Also, it is possible the OWCs may improve the platform dynamic performance by providing positive damping through controlling the air turbine rotational speed. In this work, we describe the geometry properties of the proposed WindOWC concept and conduct preliminary hydrodynamic analysis using potential flow theory. The ANSYS AQWA is used to obtain the system dynamic responses in frequency and time domain, respectively. The OWC dynamics and expected positive damping from them will be investigated in the future.


Author(s):  
Chenyu Luan ◽  
Constantine Michailides ◽  
Zhen Gao ◽  
Torgeir Moan

Semi-submersible floating structures might be an attractive system to support wind turbines and wave energy converters (WECs) in areas with abundant wind and wave energy resources. The combination of wind turbines and WECs may increase the total power production and reduce the cost of the power. A concept of a semi-submersible with a 5 MW horizontal axis wind turbine combined with three flap-type WECs is presented in this paper. The concept is named as Semi-submersible Flap Combination (SFC). The WECs of the SFC are inspired by an optimized bottom-fixed rotating flap-type wave energy absorber. Each WEC of SFC includes an elliptical cylinder, two supporting arms, a rotational axis and a power take off (PTO) system. A time domain numerical modeling method for the SFC is presented. The numerical model is using the state-of-the-art code Simo/Riflex/Aerodyn. Linear rotational damping is introduced to model the effects of the PTO system. The choice of a PTO damping coefficient and of the mass of the elliptical cylinders has a significant effect on the power generated by the WECs. Such effects have been addressed and discussed in the paper through a sensitivity study.


Author(s):  
Constantine Michailides ◽  
Chenyu Luan ◽  
Zhen Gao ◽  
Torgeir Moan

In the present paper the effect of flap type wave energy converters on the response of a floating semi-submersible wind turbine is investigated and reported. Two different layouts with regard to the number of rotating flaps that are utilized are considered and compared with the case of a pure floating semi-submersible wind turbine. Comparisons of response in terms of stability, motions and internal loads are made for selected environmental conditions. The combined operation of the rotating flaps results in an increase of the produced power without affecting significantly selected critical response quantities of the semi-submersible platform.


Author(s):  
Rony JS ◽  
Debabrata Karmakar

Abstract The combined offshore wind and wave energy on an integrated platform is an economical solution for the offshore energy industry as they share the infrastructure and ocean space. The study presents the dynamic analysis of the Submerged Tension-Leg Platform (STLP) combined with a heaving-type point absorber wave energy converter (WEC). The feasibility study of the hybrid concept is performed using the aero-servo-hydro-elastic simulation tool FAST. The study analyses the responses of the combined system to understand the influence of the WECs on the STLP platform for various operating conditions of the wind turbine under regular and irregular waves. A positive synergy is observed between the platform and the WECs, and the study also focuses on the forces and moments developed at the interface of the tower and platform to understand the effect of wind energy on the turbine tower and importance of motion amplitudes on the performance of the combined platform system. The mean and standard deviation for the translation and rotational motions of combined wind and wave energy converters are determined for different sea states under both regular and irregular waves to analyse the change in responses of the structure. The study observed a reduction in motion amplitudes of the hybrid floating system with the addition of the wave energy converters around the STLP floater to improve the energy efficiency of the hybrid system. The study helps in understanding the best possible arrangement of point absorber type wave energy converters at the conceptual stage of the design process.


Author(s):  
I S Arief ◽  
I K A P Utama ◽  
R Hantoro ◽  
J Prananda ◽  
T R Arvisa ◽  
...  

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