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
Author(s):  
Jian Tan ◽  
Henk Polinder ◽  
Peter Wellens ◽  
Sape Miedema

Abstract In this paper, a fair evaluation method of WECs (Wave Energy Converters) is established based on frequency domain simulation. In this fair evaluation, size optimization and downsizing of PTO (Power Take-Off) capacity are included to minimize the Cost of Energy for the concerned wave location. Based on this fair evaluation, a techno-economic evaluation of a generic point absorber is conducted for a specific wave location, and two different control strategies of PTO are considered. The results show that this fair evaluation method can contribute to the improvement of techno-economic performance of WECs. Furthermore, a comparison among three different size optimization methods of WECs is performed.


Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1665
Author(s):  
Aleix Maria-Arenas ◽  
Aitor J. Garrido ◽  
Eugen Rusu ◽  
Izaskun Garrido

The authors would like to add the following note to Figure 7 of their paper published in Energies [...]


2014 ◽  
Vol 6 ◽  
pp. 846097 ◽  
Author(s):  
Mohammed Faizal ◽  
M. Rafiuddin Ahmed ◽  
Young-Ho Lee

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.


2021 ◽  
Vol 9 (1) ◽  
pp. 52
Author(s):  
Jian Tan ◽  
Henk Polinder ◽  
Antonio Jarquin Laguna ◽  
Peter Wellens ◽  
Sape A. Miedema

Currently, the techno-economic performance of Wave Energy Converters (WECs) is not competitive with other renewable technologies. Size optimization could make a difference. However, the impact of sizing on the techno-economic performance of WECs still remains unclear, especially when sizing of the buoy and Power Take-Off (PTO) are considered collectively. In this paper, an optimization method for the buoy and PTO sizing is proposed for a generic heaving point absorber to reduce the Levelized Cost Of Energy (LCOE). Frequency domain modeling is used to calculate the power absorption of WECs with different buoy and PTO sizes. Force constraints are used to represent the effects of PTO sizing on the absorbed power, in which the passive and reactive control strategy are considered, respectively. A preliminary economic model is established to calculate the cost of WECs. The proposed method is implemented for three realistic sea sites, and the dependence of the optimal size of WECs on wave resources and control strategies is analyzed. The results show that PTO sizing has a limited effect on the buoy size determination, while it can reduce the LCOE by 24% to 31%. Besides, the higher mean wave power density of wave resources does not necessarily correspond to the larger optimal buoy or PTO sizes, but it contributes to the lower LCOE. In addition, the optimal PTO force limit converges at around 0.4 to 0.5 times the maximum required PTO force for the corresponding sea sites. Compared with other methods, this proposed method shows a better potential in sizing and reducing LCOE.


2021 ◽  
pp. 487-532
Author(s):  
Marcos Blanco ◽  
Jorge Torres ◽  
Miguel Santos-Herrán ◽  
Luis García-Tabarés ◽  
Gustavo Navarro ◽  
...  

AbstractThis chapter is focused on Power Take-Off (PTO) systems for wave energy converters (WEC), being one of the most important elements since PTOs are responsible to transform the mechanical power captured from the waves into electricity. It presents Direct-Drive PTO (DDPTO) as one of the most reliable solutions to be adapted to some particular types of WEC, such as point absorbers. A discussion about modularity and adaptability, together with intrinsic characteristics of direct-drive PTOs, is also included. Among the different technologies of electric machines that can be used in direct-drive linear PTOs, switched reluctance machines (SRM) are described in further detail. In particular, the Azimuthal Multi-translator SRM is presented as a suitable solution in order to increase power density and reduce costs. Not only the electric machine, but also the associated power electronics are described in detail. The description includes the different configurations and topologies of power converters and the most appropriate control strategies. Finally, a superconducting linear generator solution is described, presenting it as a reliable alternative for the application of direct-drive PTOs. An example of concept and preliminary design is included in order to highlight the main challenges to be faced during this process.


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