Browsing by Keyword "Wave energy"
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Item Applying International Power Quality Standards for Current Harmonic Distortion to Wave Energy Converters and Verified Device Emulators(2019-09-24) Kelly, James; Aldaiturriaga, Endika; Ruiz-Minguela, Pablo; Tecnalia Research & InnovationThe push for carbon-free energy sources has helped encourage the development of the ocean renewable energy sector. As ocean renewable energy approaches commercial maturity, the industry must be able to prove it can provide clean electrical power of good quality for consumers. As part of the EU funded Open Sea Operating Experience to Reduce Wave Energy Cost (OPERA) project that is tasked with developing the wave energy sector, the International Electrotechnical Commission (IEC) developed electrical power quality standards for marine energy converters, which were applied to an oscillating water column (OWC). This was done both in the laboratory and in the real world. Precise electrical monitoring equipment was installed in the Mutriku Wave Power Plant in Spain and to an OWC emulator in the Lir National Ocean Test Facility at University College Cork in Ireland to monitor the electrical power of both. The electrical power generated was analysed for harmonic current distortion and the results were compared. The observations from sea trials and laboratory trials demonstrate that laboratory emulators can be used in early stage development to identify the harmonic characteristics of a wave energy converter.Item Comparative assessment of control strategies for the biradial turbine in the Mutriku OWC plant(2020-02) Faÿ, François-Xavier; Henriques, João C.; Kelly, James; Mueller, Markus; Abusara, Moahammad; Sheng, Wanan; Marcos, Marga; Tecnalia Research & Innovation; RENOVABLES EFICIENCIA ENERGETICA Y CIRCULARIDADTo be competitive against other renewable energy sources, energy converted from the ocean waves needs to reduce its associated levelised cost of energy. It has been proven that advanced control algorithms can increase power production and device reliability. They act throughout the power conversion chain, from the hydrodynamics of wave absorption to the power take-off to improve the energy yield. The present work highlights the development and test of several algorithms to control the biradial turbine which is to be installed in the Mutriku oscillating water column plant. A collection of adaptive and predictive controllers is explored and both turbine speed controllers and latching strategies are examined. A Wave-to-Wire model of one chamber of the plant is detailed and simulation results of six control laws are obtained. The controllers are then validated using an electrical test infrastructure to prepare the future deployment in the plant. Finally, the control strategies are assessed against criteria like energy production, power quality or reliability.Item Control strategies for combining local energy storage with wells turbine oscillating water column devices(2015-11-01) Ceballos, Salvador; Rea, J.A.; Robles, Eider; Lopez, Iraide; Pou, Josep; O´Sullivan, D.; O'Sullivan, Dara; POWER ELECTRONICS AND SYSTEM EQUIPMENT; RENOVABLES OFFSHOREThis paper proposes three generator control strategies for Wells turbine-based floating oscillating wáter column (OWC) devices comprising electrical or mechanical energy storage systems. The first control strategy is indicated for low inertia turbine OWC devices that include ultracapacitors. This control law optimizes the power take-off efficiency by means of an instantaneous speed controller that allows variation of the turbine rotational speed in a wave-by-wave basis. In addition, the profile of the electrical power injected into the grid is smoothed, so that a high penetration of wave energy does not threaten the grid stability. The second and third control laws are developed for OWC systems comprising a flywheel. Quasi-constant and variable speed controllers are proposed. These control laws do not maximize the system efficiency but allow the use of simpler, smaller and cheaper power electronics. Additionally the power quality is also optimized. The development of the proposed control algorithms is accomplished by means of simulations and verified with an experimental test rig.Item Installation, operation and maintenance of offshore renewables(Institution of Engineering and Technology, 2019-01-01) Nava, Vincenzo; Ruiz-Minguela, Pablo; Pérez-Morán, Germán; Rodríguez-Arias, Raúl; Lopez-Mendia, Joseba; Villate-Martínez, José Luis; RENOVABLES OFFSHORE; Tecnalia Research & Innovation; GENERALThe chapter deals with the basic concepts of installation, operation and maintenance of offshore renewable energy systems. Whilst focus is given to the offshore wind industry, the extension to ocean energy (wave and tidal) offers a wider perspective on the major issues concerning the installation and maintenance. A reliability-based approach has been adopted for the analysis of the failures, providing an overview about the most common functional decomposition methodologies as well as logistic requirements for the different operations at the various stages of the lifetime of an offshore renewable project. The economic modelling of the operations, based on strategies for their planning, briefly completes the chapter.Item An Iterative Refining Approach to Design the Control of Wave Energy Converters with Numerical Modeling and Scaled HIL Testing(2020-05) Delmonte, Nicola; Robles, Eider; Cova, Paolo; Giuliani, Francesco; Faÿ, François Xavier; Lopez, Joseba; Ruol, Piero; Martinelli, Luca; Tecnalia Research & Innovation; RENOVABLES OFFSHORE; RENOVABLES EFICIENCIA ENERGETICA Y CIRCULARIDADThe aim of this work is to show that a significant increase of the e_ciency of aWave Energy Converter (WEC) can be achieved already at an early design stage, through the choice of a turbine and control regulation, by means of an accurate Wave-to-Wire (W2W) modeling that couples the hydrodynamic response calibrated in a wave flume to a Hardware-In-the-Loop (HIL) test bench with sizes and rates not matching those of the system under development. Information on this procedure is relevant to save time, because the acquisition, the installation, and the setup of a test rig are not quick and easy. Moreover, power electronics and electric machines to emulate turbines and electric generators matching the real systems are not low-cost equipment. The use of HIL is important in the development of WECs also because it allows the carrying out of tests in a controlled environment, and this is again time- and money-saving if compared to tests done on a real system installed at the sea. Furthermore, W2W modeling can be applied to several Power Take-O_ (PTO) configurations to experiment di_erent control strategies. The method here proposed, concerning a specific HIL for testing power electronics and control laws for a specific WECs, may have a more general validity.Item Latching control of a floating oscillating-water-column wave energy converter(2016-05-01) Henriques, J. C.C.; Gato, L. M.C.; Falcão, A. F.O.; Robles, E.; Faÿ, F. X.; RENOVABLES OFFSHORE; RENOVABLES EFICIENCIA ENERGETICA Y CIRCULARIDADThe OWC spar-buoy is an axisymmetric floating version of an oscillating-water-column (OWC) based device whose power take-off (PTO) system is an air turbine/generator set. Latching has been regarded as one of the most promising techniques to improve the efficiency of wave energy converters. In the case of the OWC spar-buoy, latching control is performed by opening/closing a high-speed stop valve installed in series with the turbine. The present paper has three main objectives. Firstly, to assess the performance improvements that can be achieved with a latching control strategy within a receding horizon framework. Secondly, to establish the practical requirements of this type of control by evaluating the sensitivity of the turbine power output to several receding horizon time intervals. Finally, to test and validate experimentally the proposed algorithms in a small-scale PTO test rig. All the experimental tests were performed considering irregular wave conditions.Item Numerical Simulation of Control Strategies at Mutriku Wave Power Plant(American Society of Mechanical Engineers (ASME), 2018) Faÿ, François-Xavier; Kelly, James; Henriques, João; Pujana, Ainhoa; Abusara, Mohammad; Mueller, Markus; Touzon, Imanol; Ruiz-Minguela, Pablo; Tecnalia Research & Innovation; RENOVABLES EFICIENCIA ENERGETICA Y CIRCULARIDAD; DIGITAL ENERGY; RENOVABLES OFFSHOREIn order to de-risk wave energy technologies and bring confidence to the sector, it is necessary to gain experience and collect data from sea trials. As part of the OPERA H2020 project, the Mutriku Wave Power Plant (MWPP) is being used as a real condition laboratory for the experiment of innovative technologies. The plant is situated in the North shore of Spain and has been operating since 2011. It uses the Oscillating Water Column (OWC) principle, which consists in compressing and expanding the air trapped in a chamber due to the inner free-surface oscillation resulting from the incident waves. The pressure difference between the air chamber and the atmosphere is used to drive an air turbine. In that case, a self-rectifying air turbine is the best candidate for the energy conversion, as it produces a unidirectional torque in presence of a bi-directional flow. The power take-off system installed is composed of a biradial turbine connected to a 30kW off-the-shelf squirrel cage generator. One of the novelties of the turbine is a high-speed stop-valve installed close to the rotor. The valve may be used to control the flow rate through the turbine or for latching control. This paper focuses on the development, the implementation and the numerical simulation of five control strategies including turbine speed and generator torque controllers. The algorithms were designed thanks to a numerical model describing one of the OWC chambers of the Mutriku power plant. Numerical results are presented for a variety of sea states and a comparison between the proposed control laws in terms of energy production and power quality is performed.Item Ocean Energy Systems Wave Energy Modelling Task: Modelling, Verification and Validation of Wave Energy Converters: Modelling, verification and validation ofwave energy converters(2019) Wendt, Fabian; Nielsen, Kim; Yu, Yi-Hsiang; Bingham, Harry; Eskilsson, Claes; Kramer, Morten; Babarit, Aurelien; Bunnik, Tim; Costello, Ronan; Crowley, Sarah; Gendron, Bengamin; Giorgi, Giuseppe; Girardin, Samuel; Greaves, Devorah; Heras, Pilar; Hoffman, Johan; Islam, Hafizul; Jakobsen, Ken-Robert; Janson, Carl-Erik; Jansson, Johan; Kim, Hyun Yul; Kurniawan, Adi; Leoni, Massimiliano; Mathai, Thomas; Nam, Bo-Woo; Park, Sewan; Rajagopalan, Krishnakumar; Ransley, Edward; Read, Robert; Ringwood, John V.; Rodrigues, Jose Miguel; Rosenthal, Benjamin; Roy, Andre; Ruehl, Kelley; Schofield, Paul; Sheng, Wanan; Shiri, Abolfazl; Thomas, Sarah; Touzon, Imanol; Yasutaka, Imai; Giorgi, Simone; Kim, Jeong-Seok; Kim, Kyong-Hwan; Gendron, Benjamin; Greaves, Deborah; Schofield, Paul; Tecnalia Research & InnovationThe International Energy Agency Technology Collaboration Programme for Ocean Energy Systems (OES) initiated the OES Wave Energy Conversion Modelling Task, which focused on the verification and validation of numerical models for simulating wave energy converters (WECs). The long-term goal is to assess the accuracy of and establish confidence in the use of numerical models used in design as well as power performance assessment of WECs. To establish this confidence, the authors used different existing computational modelling tools to simulate given tasks to identify uncertainties related to simulation methodologies: (i) linear potential flow methods; (ii) weakly nonlinear Froude–Krylov methods; and (iii) fully nonlinear methods (fully nonlinear potential flow and Navier–Stokes models). This article summarizes the code-to-code task and code-to-experiment task that have been performed so far in this project, with a focus on investigating the impact of different levels of nonlinearities in the numerical models. Two different WECs were studied and simulated. The first was a heaving semi-submerged sphere, where free-decay tests and both regular and irregular wave cases were investigated in a code-to-code comparison. The second case was a heaving float corresponding to a physical model tested in a wave tank. We considered radiation, diffraction, and regular wave cases and compared quantities, such as the WEC motion, power output and hydrodynamic loading.Item Review of Systems Engineering (SE) Methods and Their Application to Wave Energy Technology Development(2020-10-20) Ruiz‐minguela, Pablo; Nava, Vincenzo; Hodges, Jonathan; Blanco, Jesús M.; RENOVABLES OFFSHOREThe design of effective and economically viable wave energy devices involves complex decision-making about the product based on conceptual design information, including stakeholder requirements, functions, components and technical parameters. The great diversity of concepts makes it extremely difficult to create fair comparisons of the relative merits of the many different designs. Conventional design approaches have proved insufficient to guarantee wave energy technologies meet their technical and economic goals. Systems engineering can provide a suitable framework to overcome the obstacles towards a successful wave energy technology. The main objective of this work is to review the well-established systems engineering approaches that have been successfully implemented in complex engineering problems and to what extent they have been applied to wave energy technology development. The paper first reviews how system information can be organised in different design domains to guide the synthesis and analysis activities and the definition of requirements and metrics, as well as the search for solutions and decision-making. Then, an exhaustive literature review on the application of systems engineering approaches to wave energy development is presented per design domain. Finally, a set of conclusions is drawn, along with some suggestions for improving the effectiveness of wave energy technology development.Item Sea trial results of a predictive algorithm at the Mutriku Wave power plant and controllers assessment based on a detailed plant model(2020-02) Faÿ, François-Xavier; Robles, Eider; Marcos, Marga; Aldaiturriaga, Endika; Camacho, Eduardo F.; Tecnalia Research & Innovation; RENOVABLES EFICIENCIA ENERGETICA Y CIRCULARIDAD; RENOVABLES OFFSHOREImproving the power production in wave energy plants is essential to lower the cost of energy production from this type of installations. Oscillating Water Column is among the most studied technologies to convert the wave energy into a useful electrical one. In this paper, three control algorithms are developed to control the biradial turbine installed in the Mutriku Wave Power Plant. The work presents a comparison of their main advantages and drawbacks first from numerical simulation results and then with practical implementation in the real plant, analysing both performance and power integration into the grid. The wave-to-wire model used to develop and assess the controllers is based on linear wave theory and adjusted with operational data measured at the plant. Three different controllers which use the generator torque as manipulated variable are considered. Two of them are adaptive controllers and the other one is a nonlinear Model Predictive Control (MPC) algorithm which uses information about the future waves to compute the control actions. The best adaptive controller and the predictive one are then tested experimentally in the real power plant of Mutriku, and the performance analysis is completed with operational results. A real time sensor installed in front of the plant gives information on the incoming waves used by the predictive algorithm. Operational data are collected during a two-week testing period, enabling a thorough comparison. An overall increase over 30% in the electrical power production is obtained with the predictive control law in comparison with the reference adaptive controller.