Rotational speed control and electrical rated power of an oscillating-water-column wave energy converter

Energy ◽  
2017 ◽  
Vol 120 ◽  
pp. 253-261 ◽  
Author(s):  
A.F.O. Falcão ◽  
J.C.C. Henriques ◽  
L.M.C. Gato
Author(s):  
João C. C. Henriques ◽  
Juan C. Chong ◽  
António F. O. Falcão ◽  
Rui P. F. Gomes

The paper concerns the phase control by latching of a floating oscillating-water-column (OWC) wave energy converter of spar-buoy type in irregular random waves. The device is equipped with a two-position fast-acting valve in series with the turbine. The instantaneous rotational speed of the turbine is controlled through the power electronics according to a power law relating the electromagnetic torque on the generator rotor to the rotational speed, an algorithm whose adequacy had been numerically tested in earlier papers. Two alternative strategies (1 and 2) for the latching/unlatching timings are investigated. Strategy 1 is based on the knowledge of the zero-crossings of the excitation force on the floater-tube set. This is difficult to implement in practice, since the excitation force can neither be measured directly nor predicted. Strategy 2 uses as input easily measurable physical variables: air pressure in the chamber and turbine rotational speed. Both strategies are investigated by numerical simulation based on a time-domain analysis of a spar-buoy OWC equipped with a self-rectifying radial-flow air turbine of biradial type. Air compressibility in the chamber plays an important role and was modelled as isentropic in a fully non-linear way. Numerical results show that significant gains up to about 28% are achievable through strategy 1, as compared with no phase control. Strategy 2, while being much easier to implement in practice, was found to yield more modest gains (up to about 15%).


2015 ◽  
pp. 437-443
Author(s):  
Harry Bingham ◽  
Robert Read ◽  
Frederik Jakobsen ◽  
Morten Simonsen ◽  
Pablo Guillen ◽  
...  

2021 ◽  
Vol 11 (18) ◽  
pp. 8630
Author(s):  
Yuri Theodoro Barbosa de Lima ◽  
Mateus das Neves Gomes ◽  
Liércio André Isoldi ◽  
Elizaldo Domingues dos Santos ◽  
Giulio Lorenzini ◽  
...  

The work presents a numerical study of a wave energy converter (WEC) device based on the oscillating water column (OWC) operating principle with a variation of one to five coupled chambers. The main objective is to evaluate the influence of the geometry and the number of coupled chambers to maximize the available hydropneumatic power converted in the energy extraction process. The results were analyzed using the data obtained for hydropneumatic power, pressure, mass flow rate, and the calculated performance indicator’s hydropneumatic power. The Constructal Design method associated with the Exhaustive Search optimization method was used to maximize the performance indicator and determine the optimized geometric configurations. The degrees of freedom analyzed were the ratios between the height and length of the hydropneumatic chambers. A wave tank represents the computational domain. The OWC device is positioned inside it, subject to the regular incident waves. Conservation equations of mass and momentum and one equation for the transport of the water volume fraction are solved with the finite volume method (FVM). The multiphase model volume of fluid (VOF) is used to tackle the water–air mixture. The analysis of the results took place by evaluating the performance indicator in each chamber separately and determining the accumulated power, which represents the sum of all the powers calculated in all chambers. The turbine was ignored, i.e., only the duct without it was analyzed. It was found that, among the cases examined, the device with five coupled chambers converts more energy than others and that there is an inflection point in the performance indicator, hydropneumatic power, as the value of the degree of freedom increases, characterizing a decrease in the value of the performance indicator. With the results of the hydropneumatic power, pressure, and mass flow rate, it was possible to determine a range of geometry values that maximizes the energy conversion, taking into account the cases of one to five coupled chambers and the individual influence of each one.


Author(s):  
Andrei Santos ◽  
Filipe Branco Teixeira ◽  
Liércio Isoldi ◽  
jeferson Avila Souza ◽  
Mateus das Neves Gomes ◽  
...  

Author(s):  
Frances M. Judge ◽  
Eoin Lyden ◽  
Michael O'Shea ◽  
Brian Flannery ◽  
Jimmy Murphy

Abstract This research presents a methodology for carrying out uncertainty analysis on measurements made during wave basin testing of an oscillating water column wave energy converter. Values are determined for Type A and Type B uncertainty for each parameter of interest, and uncertainty is propagated using the Monte Carlo method to obtain an overall Expanded Uncertainty with a 95% confidence level associated with the Capture Width Ratio of the device. An analysis into the impact of reflections on the experimental results reveals the importance of identifying the incident and combined wave field at each measurement location used to determine device performance, in order to avoid misleading results.


2015 ◽  
Vol 82 ◽  
pp. 766-773 ◽  
Author(s):  
Sebastian Brusca ◽  
Filippo Cucinotta ◽  
Antonio Galvagno ◽  
Rosario Lanzafame ◽  
Stefano Mauro ◽  
...  

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