scholarly journals Optimisation of wave-power arrays without prescribed geometry over incident wave angle

2021 ◽  
Vol 4 (1) ◽  
pp. 1-10
Author(s):  
Justin McGuinness ◽  
Gareth Thomas
Keyword(s):  
Objective Function ◽  
Incident Wave ◽  
Linear Arrays ◽  
Point Absorber ◽  
Wave Energy Converters ◽  
Interaction Factor ◽  
Incident Wave Angle ◽  
The Mean ◽  
Objective Function Values ◽  
Wave Angle

This paper describes the optimisation of arrays of wave energy converters (WECs) of point absorber type. The WECs are spherical in shape and operate in heave only. Previous work is extended to an optimisation of array layouts without a prescribed geometry. The objective function is chosen as the mean of the array interaction factor over a prescribed range of incident wave angles. This formulation forces the array to perform optimally over a specified range of wave angle, without direct concern for wavelength variations. Both constrained and unconstrained WEC motions are considered, with constrained optimisations limiting device displacements to two or three times the incident wave amplitude. The increased freedom in this more general optimisation results in a 70% to 140% increase in objective function values compared to the analogous linear array optimisations. As in previous studies of this nature, unconstrained arrays tend to contain closely spaced WECs and larger displacement amplitudes, whereas constrained optimal arrays are more widely spaced. It is shown that the prescribed range of incident wave angle has a great effect on the optimal array layout, with better performance achieved for smaller ranges of wave angle due to better tuning of the array members. A previously identified trade-off in linear arrays, between performance stability to different incident wave parameters, is shown not to apply to general array layouts.

Optimising Reactive Control in Non-Ideal Efficiency Wave Energy Converters

2014 ◽  
Author(s):  
T. Strager ◽  
A. Martin dit Neuville ◽  
P. Fernández López ◽  
G. Giorgio ◽  
T. Mureşan ◽  
...  
Keyword(s):  
Optimal Control ◽  
Wave Energy ◽  
Electrical Power ◽  
Control Parameters ◽  
Reactive Control ◽  
Simple Method ◽  
Point Absorber ◽  
Wave Energy Converters ◽  
The Mean ◽  
Energy Converters

When analytically optimising the control strategy in wave energy converters which use a point absorber, the efficiency aspect is generally neglected. The results presented in this paper provide an analytical expression for the mean harvested electrical power in non-ideal efficiency situations. These have been derived under the assumptions of monochromatic incoming waves and linear system behaviour. This allows to establish the power factor of a system with non-ideal efficiency. The locus of the optimal reactive control parameters is then studied and an alternative method of representation is developed to model the optimal control parameters. Ultimately we present a simple method of choosing optimal control parameters for any combination of efficiency and wave frequency.

scholarly journals Hydrodynamic Sensitivity of Moored and Articulated Multibody Offshore Structures in Waves

2021 ◽  
Vol 9 (9) ◽  
pp. 1028
Author(s):  
Changqing Jiang ◽  
Ould el Moctar ◽  
Thomas E. Schellin
Keyword(s):  
Incident Wave ◽  
Critical Phenomenon ◽  
Building Blocks ◽  
Offshore Structures ◽  
Hydrodynamic Characteristics ◽  
Mooring Line ◽  
Mooring Lines ◽  
Weakly Nonlinear ◽  
Incident Wave Angle ◽  
Wave Angle

Within the framework of Space@Sea project, an articulated modular floating structurewas developed to serve as building blocks for artificial islands. The modularity was one of the keyelements, intended to provide the desired flexibility of additional deck space at sea. Consequently, the layout of a modular floating concept may change, depending on its functionality and environmental condition. Employing a potential-flow-based numerical model (i.e., weakly nonlinear Green function solver AQWA), this paper studied the hydrodynamic sensitivity of such multibody structures to the number of modules, to the arrangement of these modules, and to the incident wave angle. Results showed that for most wave frequencies, their hydrodynamic characteristics were similar although the floating platforms consisted of a different number of modules. Only translational horizontal motions, i.e., surge and sway, were sensitive to the incident wave angle. The most critical phenomenon occurred at head seas, where waves traveled perpendicularly to the rotation axes of hinged joints, and the hinge forces were largest. Hydrodynamic characteristics of modules attached behind the forth module hardly changed. The highest mooring line tensions arose at low wave frequencies, and they were caused by second-order mean drift forces. First-order forces acting on the mooring lines were relatively small. Apart from the motion responses and mooring tensions, forces acting on the hinge joints governed the system’s design. The associated results contribute to design of optimal configurations of moored and articulated multibody floating islands. 

Study on the Generated Power Changes by the Relation Between an Arrangement of an Array of Point Absorber Type WECs and an Incident Wave Angle

2019 ◽  
Author(s):  
Motohiko Murai ◽  
Qiao Li ◽  
Junki Funada
Keyword(s):  
Renewable Energy ◽  
Electric Power ◽  
Wave Energy ◽  
Past Research ◽  
Hydrodynamic Interactions ◽  
Control Force ◽  
Marine Renewable Energy ◽  
Point Absorber ◽  
Wave Energy Converters ◽  
Wave Angle

Abstract Using marine renewable energy can contribute providing the energy instead of using fossil fuel. There are some types of marine renewable energy. Wave energy is one of these and no one doubts its vast potential once they glance the sea. The object of this paper is an array of Point Absorber Wave Energy Converters (PA-WECs). In the array, complex hydrodynamic interactions among the array will occur. The interaction influences the wave power density among the array both increase and decrease. When we consider the maximization of generated electric power of the array, the suitable choice of the control force of the generator taken into a positive effect of the hydrodynamic interactions is the key. In the past research, as for a detection of the suitable control force of a single PA-WEC it has been shown the analytical solution within linear system. In this paper, we show the numerical solution of the control force parameter for maximizing the generated electric power of the array taking the hydrodynamic interaction among the array both in diffraction and radiation problem into account. Then we carried out the numerical examination and discussed the good arrangement of an array in waves based on the proposed method and an effect of the choice of the best and better control force.

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