Experimental and numerical comparisons of self-reacting point absorber wave energy converters in irregular waves

Currently, a number of wave energy converters are being analyzed by means of numerical models in order to predict the electrical power generation under given wave conditions. A common characteristic of this procedure is to integrate the loadings from the hydrodynamics, power take-off and mooring systems into a central wave to wire model. The power production then depends on the control strategy which is applied to the device. The objective of this paper is to develop numerical methods for motion analysis of marine structures with a special emphasis on wave energy converters. Two different time domain models are applied to a point absorber system working in pitch mode only. The device is similar to the well-known Wavestar prototype located in the Danish North Sea. A laboratory model has been set up in order to validate the numerical simulations of the dynamics. Wave Excitation force and the response of the device for regular and irregular waves were measured. Good correspondence is found between the numerical and the physical model for relatively mild wave conditions. For higher waves the numerical model seems to underestimate the response of the device due to its linear fluid-structure interaction assumption and linearized equation of motion. The region over which the numerical model is valid will be presented in terms of non-dimensional parameters describing the different wave states.

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Point Absorber Wave Energy Converters in Regular and Irregular Waves with Time Domain Analysis

International Journal of Marine Science and Ocean Technology ◽

10.19070/2577-4395-1600011 ◽

2016 ◽

pp. 74-85

Author(s):

Fuat Kara ◽

Keyword(s):

Wave Energy ◽

Time Domain ◽

Time Domain Analysis ◽

Domain Analysis ◽

Irregular Waves ◽

Point Absorber ◽

Wave Energy Converters ◽

Energy Converters

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Coupled dynamic analysis of hybrid offshore wind turbine and wave energy converter

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.4052936 ◽

2021 ◽

pp. 1-40

Author(s):

Rony JS ◽

Debabrata Karmakar

Keyword(s):

Dynamic Analysis ◽

Wind Turbine ◽

Wave Energy ◽

Wave Energy Converter ◽

Offshore Wind ◽

Irregular Waves ◽

Energy Converter ◽

Point Absorber ◽

Wave Energy Converters ◽

Energy Converters

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.

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Performance assessments of the fully submerged sphere and cylinder point absorber wave energy converters

Modern Physics Letters B ◽

10.1142/s0217984919501689 ◽

2019 ◽

Vol 33 (13) ◽

pp. 1950168 ◽

Cited By ~ 2

Author(s):

Qianlong Xu ◽

Ye Li ◽

Yingkai Xia ◽

Weixing Chen ◽

Feng Gao

Keyword(s):

Wave Height ◽

Wave Energy ◽

Interaction Analysis ◽

Wave Power ◽

Viscous Damping ◽

Power Performance ◽

Point Absorber ◽

Wave Energy Converters ◽

Submerged Sphere ◽

Energy Converters

Fully submerged sphere and cylinder point absorber (PA), wave energy converters (WECs) are analyzed numerically based on linearized potential flow theory. A boundary element method (BEM) (a radiation–diffraction panel program for wave-body interactions) is used for the basic wave-structure interaction analysis. In the present numerical model, the viscous damping is modeled by an equivalent linearized damping which extracts the same amount of wave energy over one cycle as the conventional quadratic damping term. The wave power capture width in each case is predicted. Comparisons are also made between the sphere and cylinder PAs which have identical geometrical scales and submerged depths. The results show that: (i) viscous damping has a greater influence on wave power performance of the cylinder PA than that of the sphere PA; (ii) the increasing wave height reduces wave power performance of PAs; (iii) the cylinder PA has a better wave power performance compared to the sphere PA in larger wave height scenarios, which indicates that fully submerged cylinder PA is a preferable prototype of WEC.

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