scholarly journals Influence of Time and Frequency Domain Wave Forcing on the Power Estimation of a Wave Energy Converter Array

2020 ◽  
Vol 8 (3) ◽  
pp. 171
Author(s):  
Fadia Ticona Rollano ◽  
Thanh Toan Tran ◽  
Yi-Hsiang Yu ◽  
Gabriel García-Medina ◽  
Zhaoqing Yang
Keyword(s):  
Power Systems ◽  
Wave Energy ◽  
Time Domain ◽  
Power Output ◽  
Wave Model ◽  
Phase Information ◽  
Wave Forcing ◽  
Marine Renewable Energy ◽  
Wave Energy Converters ◽  
Averaged Model

Industry-specific tools for analyzing and optimizing the design of wave energy converters (WECs) and associated power systems are essential to advancing marine renewable energy. This study aims to quantify the influence of phase information on the device power output of a virtual WEC array. We run the phase-resolving wave model FUNWAVE-TVD (Total Variation Diminishing) to generate directional waves at the PacWave South site offshore from Newport, Oregon, where future WECs are expected to be installed for testing. The two broad cases presented correspond to mean wave climates during warm months (March–August) and cold months (September–February). FUNWAVE-TVD time series of sea-surface elevation are then used in WEC-Sim, a time domain numerical model, to simulate the hydrodynamic response of each device in the array and estimate their power output. For comparison, WEC-Sim is also run with wave energy spectra calculated from the FUNWAVE-TVD simulations, which do not retain phase information, and with wave spectra computed using the phase-averaged model Simulating WAves Nearshore (SWAN). The use of spectral data in WEC-Sim requires a conversion from frequency to time domain by means of random superposition of wave components, which are not necessarily consistent because of the linear assumption implicit in this method. Thus, power response is characterized by multiple realizations of the wave climates.

Assimilating a Time-Domain Representation of a Wave Energy Converter Into a Spectral Wave Model

2016 ◽  
Author(s):  
Ewelina Luczko ◽  
Helen Bailey ◽  
Bryson Robertson ◽  
Clayton Hiles ◽  
Bradley Buckham
Keyword(s):  
Wave Height ◽  
Incident Wave ◽  
Wave Energy ◽  
Time Domain ◽  
Source Code ◽  
Wave Spectrum ◽  
Wave Model ◽  
Power Production ◽  
Wave Energy Converters ◽  
Six Degree Of Freedom

To accommodate future power demands, wave energy converters (WECs) will be deployed in arrays, but largely unanswered questions of the annual energy production and environmental impact of such installations present regulatory dilemmas. In recent years, Sandia National Laboratories (SNL) has developed a modified version of the Simulating Waves Nearshore (SWAN) wave model to simulate WEC energy extraction in a propagating wave field. The SNL source code modifications to SWAN have facilitated a way to characterize the frequency dependent power absorption of a device in a spectral model using standard WEC parameterizations. The work presented in this paper seeks to build on source code modifications previously made by SNL. A new WEC meta-model, alters the incident wave spectrum based on power extracted from the sea and dissipated by hydrodynamic losses experienced at the WEC. These losses are calculated in an external six degree of freedom (DOF) time domain WEC simulation. The two WEC models were compared in terms of significant wave height reduction in the WEC’s lee and annual power production. The new model reduced the estimated distance required for the waves to recover 95% of the incident wave height by 50% for the same sea state. A 4.5% difference in annual power production was observed for a WEC operating in the lee of another device when deployed off the west coast of Canada.

Genetic Optimization of Shape and Control of Non-Linear Wave Energy Converters

2020 ◽  
Author(s):  
Jiajun Song ◽  
Ossama Abdelkhalik ◽  
Shangyan Zou
Keyword(s):  
Wave Energy ◽  
Time Domain ◽  
Optimization Approach ◽  
Linear Wave ◽  
Variable Size ◽  
Wave Energy Converters ◽  
Hydrostatic Force ◽  
Non Linear ◽  
The Time Domain ◽  
Energy Converters

Abstract This paper presents an optimization approach to design ax-isymmetric wave energy converters (WECs) based on a nonlinear hydrodynamic model. This paper shows optimal nonlinear shapes of buoy can be generated by combing basic shapes in an optimal sense. The time domain non-linear Froude-Krylov force can be computed for a complex buoy shape, by adopting analytical formulas of its basic shape components. The time domain Forude-Krylov force is decomposed into its dynamic and static components, and then contribute to the calculation of the excitation force and the hydrostatic force. A non-linear control is assumed in the form of the combination of linear and nonlinear damping terms. A variable size genetic algorithm (GA) optimization tool is developed to search for the optimal buoy shape along with the optimal control coefficients simultaneously. Chromosome of the GA tool is designed to improve computational efficiency and to leverage variable size genes to search for the optimal non-linear buoy shape. Different criteria of wave energy conversion can be implemented by the variable size GA tool. Simulation results presented in this paper show that it is possible to find non-linear buoy shapes and non-linear controllers that take advantage of non-linear hydrodynamics to improve energy harvesting efficiency with out adding reactive terms to the system.

Study on the Layout of Water-Filled Raft WEC in Wave Farm

2012 ◽  
Vol 253-255 ◽  
pp. 670-673
Author(s):  
Zhi Gang Bai ◽  
Lian Bo Shi
Keyword(s):  
Wave Energy ◽  
Power Output ◽  
Electricity Generation ◽  
Design Environment ◽  
Engineering Software ◽  
Wave Energy Converters ◽  
The World ◽  
New Type ◽  
Type Water ◽  
Wave Farm

Wave energy is recognized as an important pollution-free source of power generation in the world. So in last decades wide variety of wave energy converters (WEC) has been developed, meanwhile, more economical and reliable technologies were also under process. It is very vital to decide about the location of the WECs in a wave farm, which can increase the electricity generation [1]. To get the optimum power output, it is necessary to evaluate the layout of WECs by computer simulations, such as SWAN, MIKE21, SWASH, etc [2]. Among them, MIKE21 is a professional modeling and simulation engineering software, and is well known as a tool that provides a design environment for engineering, coastal management and planning applications. So, in this paper, MIKE21 BW was introduced briefly and applied to simulate and calculate the wave parameters of the Chengshantou wave farm, then, the layout of a new-type (Water-filled raft) WECs in the Chengshantou wave farm which can generate higher possible power output was investigated and the optimum scheme was achieved finally.

scholarly journals Balancing Power Output and Structural Fatigue of Wave Energy Converters by Means of Control Strategies

Energies ◽  
2014 ◽  
Vol 7 (4) ◽  
pp. 2246-2273 ◽  
Author(s):  
Francesco Ferri ◽  
Simon Ambühl ◽  
Boris Fischer ◽  
Jens Kofoed
Keyword(s):  
Wave Energy ◽  
Power Output ◽  
Control Strategies ◽  
Structural Fatigue ◽  
Wave Energy Converters ◽  
Energy Converters

scholarly journals On the Development of an Offshore Version of the CECO Wave Energy Converter

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1036 ◽  
Author(s):  
Gianmaria Giannini ◽  
Paulo Rosa-Santos ◽  
Victor Ramos ◽  
Francisco Taveira-Pinto
Keyword(s):  
Wave Energy ◽  
Time Domain ◽  
System Performance ◽  
Energy Production ◽  
Design Methodology ◽  
The Other ◽  
Mooring System ◽  
Wave Energy Conversion ◽  
Energy Converter ◽  
Wave Energy Converters

Offshore locations present significant amounts of wave energy and free sea space, which could facilitate the deployment of larger numbers of wave energy converters (WECs) in comparison with nearshore regions. The present study aims to find a suitable design for an offshore floating version of CECO, a sloped motion WEC. For this purpose, a new design methodology is proposed in this paper for identifying and assessing possible floating configurations of CECO, which consists of four distinct set-ups obtained by varying the type of main supporting structure and the mooring system. Two options are based on spar designs and the other two on tension leg platform (TLP) designs. Based on outcomes of time-domain numerical calculations, the aforementioned configurations were assessed in terms of annual wave energy conversion and magnitude of mooring loads. Results indicate that a TLP configuration with an innovative mooring solution could increase the annual energy production by 40% with respect to the fixed version of CECO. Besides, the mooring system is found to be a key component, influencing the overall system performance.

scholarly journals A Design Outline for Floating Point Absorber Wave Energy Converters

2014 ◽  
Vol 6 ◽  
pp. 846097 ◽  
Author(s):  
Mohammed Faizal ◽  
M. Rafiuddin Ahmed ◽  
Young-Ho Lee
Keyword(s):  
Wave Energy ◽  
Power Output ◽  
Energy Resource ◽  
Wave Structure ◽  
Floating Point ◽  
Mooring Lines ◽  
Point Absorber ◽  
Wave Energy Converters ◽  
Incident Waves ◽  
Energy Converters

An overview of the most important development stages of floating point absorber wave energy converters is presented. At a given location, the wave energy resource has to be first assessed for varying seasons. The mechanisms used to convert wave energy to usable energy vary for different wave energy conversion systems. The power output of the generator will have variations due to varying incident waves. The wave structure-interaction leads to modifications in the incident waves; thus, the power output is also affected. The device has to be stable enough to prevent itself from capsizing. The point absorber will give optimum performance when the incident wave frequencies correspond to the natural frequency of the device. The methods for calculating natural frequencies for pitching and heaving systems are presented. Mooring systems maintain the point absorber at the desired location. Various mooring configurations as well as the most commonly used materials for mooring lines are discussed. An overview of scaled modelling is also presented.

The Principle of a Three-DOF Mechanism for Wave Energy Absorption

2016 ◽  
Author(s):  
Weixing Chen ◽  
Xiangdun Meng ◽  
Feng Gao
Keyword(s):  
Wave Energy ◽  
Power Output ◽  
Wave Power ◽  
Spherical Joint ◽  
Hydraulic Power ◽  
Wave Energy Converters ◽  
Major Class ◽  
Absorption Performance ◽  
Heave Motion ◽  
Four Bar Linkage

As we all know, oceans have great wave power, and many types of wave energy converters (WECs) have been invented so far. Oscillating body systems are a major class of WECs which almost only have one degree of freedom (DOF). This paper presents a three-DOF mechanism which can extract the wave power from any wave directions. The three-DOF mechanism mainly consists of a four-bar linkage and a spherical joint, which are used to capture the heave motion and the pitch and roll motions of the oscillating body respectively. The power conversion principle of the WEC is proposed and the kinematics of the mechanism is derived. Hydraulic power take-off (PTO) systems are used, which are simplified as constant torques in this study. In the end, the power absorption performance of the WEC is presented based on the system dynamics. The results show that the rated power output of the WEC is 4.3MW, and the power output of the WEC is dependent on the wave directions.

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