Maintenance Maneuver Automation for an Adapted Cylindrical Shape TEC

Rafael Morales, Lorenzo Fernández, Eva Segura and José A. Somolinos
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Rafael Morales: Escuela de Ingenieros Industriales de Albacete, Universidad de Castilla-La Mancha, 02071 Albacete, Spain
Lorenzo Fernández: Escuela de Ingenieros Industriales de Albacete, Universidad de Castilla-La Mancha, 02071 Albacete, Spain
Eva Segura: Escuela de Ingenieros Industriales de Albacete, Universidad de Castilla-La Mancha, 02071 Albacete, Spain
José A. Somolinos: Escuela Técnica Superior de Ingenieros Navales, Universidad Politécnica de Madrid, 28040 Madrid, Spain

Energies, 2016, vol. 9, issue 9, 1-16

Abstract: Several manufacturers have developed devices with which to harness tidal/current power in areas where the depth does not exceed 40 m. These are the so-called first generation Tidal Energy Converters (TEC), and they are usually fixed to the seabed by gravity. When carrying out maintenance tasks on these devices it is, therefore, necessary to remove the nacelles from their bases and raise them to the surface of the sea. They must subsequently be placed back on their bases. These tasks require special high performance ships, signifying high maintenance costs. The automation of emersion and immersion maneuvers will undoubtedly lead to lower costs, given that ships with less demanding requirements will be required for the aforementioned maintenance tasks. This research presents a simple two degrees of freedom dynamic model that can be used to control a first generation TEC that has been conceived of to harness energy from marine currents. The control of the system is carried out by means of a water ballast system located inside the nacelle of the main power unit and is used as an actuator to produce buoying vertical forces. A nonlinear control law based on a decoupling term for the closed loop depth and/or orientation control is also proposed in order to ensure adequate behavior when the TEC performs emersion and immersion maneuvers with only hydrostatic buoyancy forces. The control scheme is composed of an inner loop consisting of a linear and decoupled input/output relationship and the vector of friction and compressibility terms and an outer loop that operates with the tracking error vector in order to ensure the asymptotically exponential stability of the TEC posture. Finally, the effectiveness of the dynamic model and the controller approach is demonstrated by means of numerical simulations when the TEC is carrying out an emersion maneuver for the development of general maintenance tasks and an emersion maneuver for blade-cleaning maintenance tasks.

Keywords: tidal energy converters; marine renewable energy; dynamic modeling; nonlinear control; automatic maneuvers (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2016
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (7)

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