Estimation of Annual Energy Production of a Horizontal Cylinder Wave Energy Converter by Time-domain Analysis

2019 ◽  
Vol 22 (3) ◽  
pp. 151-158
Author(s):  
Hyebin Lee ◽  
Il-Hyoung Cho ◽  
Haeng Sik Ko ◽  
Yoon Hyeok Bae
Keyword(s):  
Wave Energy ◽  
Time Domain ◽  
Energy Production ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Horizontal Cylinder ◽  
Wave Energy Converter ◽  
Energy Converter

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.

scholarly journals Time-domain analysis of a bean-shaped multi-body floating wave energy converter with a hydraulic power take-off using WEC-Sim

Energy ◽  
2021 ◽  
Vol 223 ◽  
pp. 119985
Author(s):  
V.V.S. Sricharan ◽  
Srinivasan Chandrasekaran
Keyword(s):  
Wave Energy ◽  
Time Domain ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Wave Energy Converter ◽  
Energy Converter ◽  
Hydraulic Power ◽  
Multi Body

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.

Efficient Dynamic Analysis of Floating Bodies Nonlinear Behavior in Wave Energy Conversion

2013 ◽  
Author(s):  
P. D. Spanos ◽  
A. Richichi ◽  
F. Arena
Keyword(s):  
Wave Energy ◽  
Time Domain ◽  
Water Waves ◽  
Nonlinear Behavior ◽  
Time Domain Analysis ◽  
Wave Energy Converter ◽  
Irregular Waves ◽  
Equivalent Linearization ◽  
Energy Converter ◽  
Stiffness And Damping

Floating oscillating-bodies are a kind of wave energy converter developed for harvesting the great amount of energy related to water waves; see Falcão [1] for a review. In this paper a particular energy converter model is considered. A nonlinear analysis of its dynamic behavior is conducted both in the time and the frequency domains. The model involves a tightly moored single-body floating wave energy converter. It captures motion in the horizontal and vertical directions. The nonlinear stiffness and damping forces are functions of the horizontal and vertical displacements and velocities and make the system a nonlinear one. In addition to the time-domain analysis of the nonlinear behavior of the system, the method of equivalent linearization is used to determine iteratively the effective linear stiffness and damping matrices and the response of the buoy in the frequency domain. The analysis pertains to the surge and the heave directions response of the wave energy converter under harmonic mono-frequency excitation (regular waves). The reliability of the linearization based approach is demonstrated by comparison with time domain integration data. This approach offers the appealing feature of conducting efficiently a variety of parameter studies which can expedite preliminary evaluations, inter alia, of competing design scenarios for the energy converter. Suggestions for extending this approach to the case of fully nonlinear and random irregular waves are also included.

Assessment of Wave Energy Extraction From Seas: Numerical Validation

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Wanan Sheng ◽  
Anthony Lewis
Keyword(s):  
Numerical Simulation ◽  
Frequency Domain ◽  
Wave Energy ◽  
Time Domain ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Energy Converter ◽  
Power Capture ◽  
Power Matrix ◽  
The Time Domain

In developing a wave energy converter (WEC), assessing and rating the device is a difficult, but important issue. Conventionally, a large scaled device (maybe large enough for accommodating a power takeoff (PTO) system) or prototype device is needed to be tested in wave tanks or in seas in different wave conditions so that a power matrix for the device can be defined using scaling or interpolation/extrapolation methods. Alternatively, a pure numerical simulation in time-domain may be used for assessing the power capture capacities of wave energy devices. For the former, it is convincing, but can be especially difficult in the early stages of development, when small scaled models are normally used; and for the latter, the pure numerical simulation may not be very reliable and convincing, especially when the dynamic problem is very complicated. In this paper, a method for assessing the captured wave power for a device from its power capture response is presented. In the proposed method, a measured or calculated linear power capture response of the device is combined with wave spectrum to compute the average captured power function. Once the average captured power function is obtained, the overall average captured power corresponding to the wave state can be easily calculated. If a linear power capture response is obtained from a model test, the power assessment based on this proposed method can be very convincing and reliable. To illustrate the application of the proposed method, an example of a fully linear dynamic system, including the linear hydrodynamics of the floating structure and a linear power takeoff, is considered. For such a system, the frequency-domain analysis can be employed to obtain the performance of the floating device under waves and the power takeoff system. The hydrodynamic performance of the wave energy converter is then used to define the power capture response and to calculate the average captured power functions in different sea states. Then, the captured power of the device in different sea states, i.e, the power matrix, can be calculated, and accordingly, the device can be assessed and rated. To validate the proposed method, a time-domain analysis is also performed for a cross-check. In the time-domain analysis, the hydrodynamic coefficients and responses are first assessed in frequency-domain, and then transformed into the relevant terms by means of impulse response functions for establishing the time-domain (TD) equation. By comparing the results from frequency-domain and time-domain analyses of irregular waves, it can be concluded that the proposed wave energy capture assessment method can be used in assessing or rating the device.

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