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Author = Gilloteaux, JeanChristophe;
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Displaying Results 1  9 of 9 on page 1 of 1
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A control system for a selfreacting point absorber wave energy converter subject to constraints
(2011)
Bacelli, Giorgio; Ringwood, John; Gilloteaux, JeanChristophe
A control system for a selfreacting point absorber wave energy converter subject to constraints
(2011)
Bacelli, Giorgio; Ringwood, John; Gilloteaux, JeanChristophe
Abstract:
The problem of the maximization of the energy produced by a self reacting point absorber subject to motion restriction is addressed. The main objective is to design a control system suitable for realtime implementation. The method presented for the solution of the optimization problem is based on the approximation of the motion of the device and of the force exerted by the power take off unit by means of a linear combination of basis functions. The result is that the optimal control problem is reformulated as a non linear program where the properties of the cost function and of the constraint are affected by the choice of the basis functions. An example is described where the motion and the force are approximated using Fourier series; an optimization algorithm for the solution of the non linear program is also presented. The control system is implemented and simulated using a real sea profile measured by a waverider buoy.
http://mural.maynoothuniversity.ie/3555/
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A nonlinear potential model to predict largeamplitudesmotions: application to a multibody wave energy converter.
(2008)
Gilloteaux, JeanChristophe; Bacelli, Giorgio; Ringwood, John
A nonlinear potential model to predict largeamplitudesmotions: application to a multibody wave energy converter.
(2008)
Gilloteaux, JeanChristophe; Bacelli, Giorgio; Ringwood, John
Abstract:
The paper is dedicated to the study of nonlinear waves acting on three dimensional surfacepiercing structures. A timedomain nonlinear potentialflow model has been developed to predict the largeamplitude motions of devices in a prescribed seaway. While earlier models have been developed for single wave energy devices, this paper addresses multibody devices, with particular application to the WAVEBOB wave energy device.
http://mural.maynoothuniversity.ie/4417/
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A nonlinear extension for linear boundary element methods in wave energy device modelling
(2012)
Mérigaud, Alexis; Gilloteaux, JeanChristophe; Ringwood, John
A nonlinear extension for linear boundary element methods in wave energy device modelling
(2012)
Mérigaud, Alexis; Gilloteaux, JeanChristophe; Ringwood, John
Abstract:
To date, mathematical models for wave energy devices typically follow Cummins equation, with hydrodynamic parameters determined using boundary element methods. The resulting models are, for the vast majority of cases, linear, which has advantages for ease of computation and a basis for control design to maximise energy capture. While these linear models have attractive properties, the assumptions under which linearity is valid are restrictive. In particular, the assumption of small movements about an equilibrium point, so that higher order terms are not significant, needs some scrutiny. While this assumption is reasonable in many applications, in wave energy the main objective is to exaggerate the movement of the device through resonance, so that energy capture can be maximised. This paper examines the value of adding specific nonlinear terms to hydrodynamic models for wave energy devices, to improve the validity of such models across the full operational spectrum.
http://mural.maynoothuniversity.ie/3866/
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A predictive controller for a heaving buoy producing potable water
(2009)
Bacelli, Giorgio; Gilloteaux, JeanChristophe; Ringwood, John
A predictive controller for a heaving buoy producing potable water
(2009)
Bacelli, Giorgio; Gilloteaux, JeanChristophe; Ringwood, John
Abstract:
A model predictive controller for a wavepowered desalination unit is presented. The desalination unit is composed of a reverse osmosis membrane, and the water is pumped at high pressure through the membrane by a wave energy converter. The wave energy converter is a heaving buoy type connected to an hydraulic circuit that converts the oscillating motion of the buoy into a rectified seawater flow at high pressure. The controller acts on a throttle valve to regulate the pressure in the reverse osmosis unit in order to avoid damage to the membrane caused by excessive pressure and to improve both its longevity and the overall efficiency of the device. The control is constrained due to the rate and position limits of the throttle valve and the recovery ratio, which is the ratio between the total amount of pumped seawater and the potable water. The system is also switched and nonstationary because of the check valves used for the rectification of the seawater flow and the variat...
http://mural.maynoothuniversity.ie/2129/
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Controlinformed geometric optimisation of wave energy converters
(2010)
Gilloteaux, JeanChristophe; Ringwood, John
Controlinformed geometric optimisation of wave energy converters
(2010)
Gilloteaux, JeanChristophe; Ringwood, John
Abstract:
This paper concerns the interplay between the physical geometry of a wave energy converter (WEC) and the control strategy adopted for the converter, with the ultimate aim of optimising the energy output of the device. An energybased performance function is employed and we attempt to perform numerical optimisation of a heaving buoy employing a latching control strategy. We allow both draught and radius of the axisymmetric buoy to be adjusted using a numerical optimisation. A linear timedomain hydrodynamic program is used in order to simulate the device motion, while the optimization problem is solved by means of a simplex method. Results show the difference in the frequency response of an optimal buoy for a particular seastate designed with and without knowledge of the control system.
http://mural.maynoothuniversity.ie/3611/
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Influence of nonlinear Froude–Krylov forces on the performance of two wave energy points absorbers
(2017)
Penalba, Markel; Mérigaud, Alexis; Gilloteaux, JeanChristophe; Ringwood, John
Influence of nonlinear Froude–Krylov forces on the performance of two wave energy points absorbers
(2017)
Penalba, Markel; Mérigaud, Alexis; Gilloteaux, JeanChristophe; Ringwood, John
Abstract:
Nonlinear behaviour of wave energy converters in power production mode can be relevant depending on the seastate, the geometry or the motion of the device. Therefore, mathematical models used to simulate the behaviour of the device may need to include nonlinear effects. This paper studies the impact of modelling nonlinear Froude–Krylov forces by computing the pressure over the instantaneous wetted surface and uses a nonlinear wave theory (the Rienecker–Fenton’s theory) including nonlinear freesurface boundary conditions, to be more consistent with the computation of nonlinear Froude–Krylov forces. First, geometric nonlinearities are studied through the consideration of two heaving point absorbers with different geometrical characteristics: a truncated cylinder with a constant crosssectional area (CSA) and a sphere with a nonuniform CSA. Then, nonlinearities related to the body dynamics are studied by applying a latching control strategy, which highlights the effect of nonlinear ...
http://mural.maynoothuniversity.ie/11775/
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Influences of wave directionality on a generic point absorber.
(2009)
Gilloteaux, JeanChristophe; Ringwood, John
Influences of wave directionality on a generic point absorber.
(2009)
Gilloteaux, JeanChristophe; Ringwood, John
Abstract:
The present study deals with the influences of wave directionality on a generic point absorber. The work presented here, shows how the dynamic of axisymmetric wave energy converter can be affected when one consider a realistic wave spectrum. For this purpose a non linear numerical model was used. The fluid structure interactions are modelled by means of a bending method where the FroudeKrylov forces are non linear and the radiationdiffraction problem is solved by using a linear method. Mooring loads are modelled via a finite element method. A compliant catenary mooring system composed by 4 mooring lines is hence used. Different models of sea spectra are used to approximate a real sea spectrum. The differences between them are discussed and comparisons on the body motions are commented.
http://mural.maynoothuniversity.ie/2134/
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Nonlinear FroudeKrylov force modelling for two heaving wave energy point absorbers
(2015)
Penalba Retes, Markel; Mérigaud, Alexis; Gilloteaux, JeanChristophe; Ringwood, John
Nonlinear FroudeKrylov force modelling for two heaving wave energy point absorbers
(2015)
Penalba Retes, Markel; Mérigaud, Alexis; Gilloteaux, JeanChristophe; Ringwood, John
Abstract:
Most mathematical models used to assess the motions of waveenergy converters are linear, which may lead to significant errors as these devices can have a stronglynonlinear behaviour. This paper investigates the effects of nonlinearities in the computation of FroudeKrylov forces, which play a major role in the dynamics of the motion of heaving energy pointabsorbers, with a focus on the influence of the device’s geometry. Results show that FroudeKrylov forces nonlinearities could be negligible when the device is uncontrolled. In contrast, they become significant when control is applied to maximise motions, especially for a device whose immersed crosssectional area varies over time: in such a case latching control parameters based on a linear model can prove to be inefficient. Furthermore, although the latching control can be adapted to the nonlinear behaviour of the device by tuning parameters accordingly, the amount of power production assessed through the linear models does not...
http://mural.maynoothuniversity.ie/6669/
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State space model of a hydraulic power take off unit for wave energy conversion employing bondgraphs
(2008)
Bacelli, Giorgio; Gilloteaux, JeanChristophe; Ringwood, John
State space model of a hydraulic power take off unit for wave energy conversion employing bondgraphs
(2008)
Bacelli, Giorgio; Gilloteaux, JeanChristophe; Ringwood, John
Abstract:
In this work, the modeling of a Power Take Off (PTO) unit for a point absorber wave energy converter is described. The PTO influences the energy conversion performance by its efficiency and by the damping force exerted, which affects the motion of the body. The state space model presented gives a description of the damping force and of the internal dynamics of the PTO. The aim of this work is to develop a model for the PTO as a part of a complete wavetowire model of a wave energy converter as in Figure 1, used for the design control techniques. Figure 1: Wavetowire model structure A bondgraph is employed to model the physical system that provides transparent and methodical means of formulating state space equations and of visualizing energy transfer throughout the system. Bondgraphs have already been shown to be a very useful tool for the modeling of PTO for wave energy converters (2). The dynamic of the mathematical model is then analyzed respect to the variation of parameters...
http://mural.maynoothuniversity.ie/4419/
Displaying Results 1  9 of 9 on page 1 of 1
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