Browsing by Keyword "Oscillating Water Column"
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Item Mooring System Design Approach: A Case Study for MARMOK-A Floating OWC Wave Energy Converter(American Society of Mechanical Engineers (ASME), 2018) Touzon, Imanol; de Miguel, Borja; Nava, Vincenzo; Petuya, Victor; Mendikoa, Iñigo; Boscolo, Francesco; Tecnalia Research & Innovation; RENOVABLES OFFSHOREThis paper presents a methodology and a flowchart of steps to take for a, consistent and rapidly convergent design of catenary mooring systems. It is subsequently applied for a floating Oscillating Water Column WEC MARMOK-A developed by Oceantec Energías Marinas, in order to fulfill the technical requirements of such dynamic systems. The approach, based on the catenary equations, considers the water depth as a design scale factor for the mooring system, leading to an equivalent static mooring performance. In general, a mooring system configuration is described by the number and distribution of lines; thus, as a preprocess in the herein described procedure, a database is built for different line lengths. The main advantage of the procedure is that once that, after characterizing a mooring system configuration at a specific water depth with a specific line mass and axial stiffness, the database built can be used for any other water depth with any line mass and axial stiffness, accelerating the design optimization process. Mooring static properties are derived for a given material elastic modulus, lines’ mass and water depth. The mean offset and horizontal stiffness are afterwards derived with lines pretension and steady environmental forces (mean wave drift, current and wind) as well as maximum offset and characteristic line tensions. Finally, the process is applied for different lines pretensions to achieve an objective horizontal stiffness of the structure. The introduced procedure is presented through its application to the MARMOK-A device at a 90m depth site moored by means of a Karratu named mooring configuration. Results are presented in terms of total lines mass, device maximum expected excursion and required footprint for different horizontal stiffness and lines mass in order to give an insight of the impact on total plant cost indicators.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.