scholarly journals Frequency- and time-domain analysis of a multi-degree-of-freedom point absorber wave energy converter

2017 ◽  
Vol 9 (12) ◽  
pp. 168781401772208 ◽  
Author(s):  
Yizhi Ye ◽  
Weidong Chen
Keyword(s):  
Wave Energy ◽  
Time Domain ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Wave Energy Converter ◽  
Degree Of Freedom ◽  
Energy Converter ◽  
Point Absorber

Time Domain Modeling and Power Output for a Heaving Point Absorber Wave Energy Converter

2014 ◽  
Author(s):  
Jeremiah Pastor ◽  
Yucheng Liu
Keyword(s):  
Frequency Domain ◽  
Wave Energy ◽  
Time Domain ◽  
Power Output ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Wave Energy Converter ◽  
Energy Converter ◽  
Power Absorption ◽  
Point Absorber

This paper presents, assesses, and optimizes a point absorber wave energy converter (WEC) through numerical modeling, simulation, and analysis in time domain. Wave energy conversion is a technology especially suited for assisting in power generation in the offshore oil and gas platforms. A linear frequency domain model is created to predict the behavior of the heaving point absorber WEC system. The hydrodynamic parameters are obtained with AQWA, a software package based on boundary element methods. A linear external damping coefficient is applied to enable power absorption and an external spring force is introduced to tune the point absorber to the incoming wave conditions. The external damping coefficient and external spring forces are the control parameters, which need to be optimized to maximize the power absorption. Two buoy shapes are tested and a variety of diameters and drafts are compared. Optimal shape, draft, and diameter of the model are then determined to maximize its power absorption capacity. Based on the results generated from the frequency domain analysis, a time domain analysis was also conducted to derive the responses of the WEC in the hydrodynamic time response domain. The time domain analysis results allowed us to estimate the power output of this WEC system.

Time-Domain Diffraction Modelling With Mean Force Effects and Experimental Comparison for Slack-Moored M4 Wave Energy Converter

2019 ◽  
Author(s):  
P. K. Stansby ◽  
E. Carpintero Moreno
Keyword(s):  
Wave Energy ◽  
Time Domain ◽  
Domain Analysis ◽  
Second Order ◽  
Radiation Damping ◽  
Wave Energy Converter ◽  
Experimental Comparison ◽  
Energy Converter ◽  
Mooring Forces ◽  
Mechanical Damping

Abstract Linear diffraction modelling of irregular wave structure interaction is standard practice in both the frequency and time domains for fixed and floating bodies. This has been extended for the modular wave energy converter M4 with multiple floats and power take offs. In the time domain second-order forces assuming a stationary body have been added for floating wind energy platforms. This misses second-order, including mean, effects due to radiation damping, drag forces and the mechanical damping of wave energy conversion. If these are linearized they may be included in a frequency domain analysis. However mechanical damping and mooring forces on slack-moored platforms are generally highly nonlinear and time domain analysis is required. In this paper response is first computed with linear analysis and mechanical damping which has been shown to give reasonable prediction of experimental measurement for the response and power output of M4. The response gives the absorbed energy flux due to mechanical and radiation damping which is converted into a mean force through an average wave celerity. The model is extended to include a mooring and these mean forces; the computation is then repeated. The mean forces have negligible effect on response and associated power take off but determine the mooring forces. For a slack mooring zero stiffness is assumed. Comparing with wave basin experiments for the 6-float M4 configuration in operational conditions, mean mooring forces are generally underestimated, markedly for larger periods.

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