Variable Speed Control In Wells Turbine-Based Oscillating Water Column Devices: Optimum Rotational Speed

The effects of climate change and global warming reveal the need to find alternative sources of clean energy. In this sense, wave energy power plants, and in particular Oscillating Water Column (OWC) devices, offer a huge potential of energy harnessing. Nevertheless, the conversion systems have not reached a commercially mature stage yet so as to compete with conventional power plants. At this point, the use of new control methods over the existing technology arises as a doable way to improve the efficiency of the system. Due to the nonuniform response that the turbine shows to the rotational speed variation, the speed control of the turbo-generator may offer a feasible solution for efficiency improvement during the energy conversion. In this context, a novel speed control approach for OWC systems is presented in this paper, demonstrating its goodness and affording promising results when particularized to the Mutriku's wave power plant.This work was supported in part by the University of the Basque Country (Universidad del Pais Vasco UPV/Euskal Herriko Unibertsitatea EHU) through Project PPG17/33 and by the MINECO through the Research Project DPI2015-70075-R (MINECO/FEDER, EU), as well as to the Basque Government through Ph.D. Grant PIF PRE_2016_2_0193. The authors would like to thank the collaboration of the Basque Energy Agency (EVE) through Agreement UPV/EHUEVE23/6/2011, the Spanish National Fusion Laboratory (EURATOM-CIEMAT) through Agreement UPV/EHUCIEMAT08/190 and EUSKAMPUS - Campus of International Excellence. They would also like to thank Yago Torre-Enciso and Olatz Ajuria from EVE for their collaboration and help

Flow Control in Wells Turbines For Harnessing Maximum Wave Power

Oceans, and particularly waves, offer a huge potential for energy harnessing all over the world. Nevertheless, the performance of current energy converters does not yet allow us to use the wave energy efficiently. However, new control techniques can improve the efficiency of energy converters. In this sense, the plant sensors play a key role within the control scheme, as necessary tools for parameter measuring and monitoring that are then used as control input variables to the feedback loop. Therefore, the aim of this work is to manage the rotational speed control loop in order to optimize the output power. With the help of outward looking sensors, a Maximum Power Point Tracking (MPPT) technique is employed to maximize the system efficiency. Then, the control decisions are based on the pressure drop measured by pressure sensors located along the turbine. A complete wave-to-wire model is developed so as to validate the performance of the proposed control method. For this purpose, a novel sensor-based flow controller is implemented based on the different measured signals. Thus, the performance of the proposed controller has been analyzed and compared with a case of uncontrolled plant. The simulations demonstrate that the flow control-based MPPT strategy is able to increase the output power, and they confirm both the viability and goodness.This work was supported in part by the University of the Basque Country (UPV/EHU) through Project PPG17/33, by the MINECO through the Research Project DPI2015-70075-R (MINECO/FEDER, EU) and by the Basque Government through Elkartek. The authors would like to thank the collaboration of the Basque Energy Agency (EVE) through Agreement UPV/EHUEVE23/6/2011, the Spanish National Fusion Laboratory (EURATOM-CIEMAT) through Agreement UPV/EHUCIEMAT08/190 and EUSKAMPUS - Campus of International Excellence. They would also like to thank Yago Torre-Enciso and Olatz Ajuria from EVE for their collaboration and help. The authors would also like to thank the anonymous reviewers that have helped to improve the initial version of the manuscript

Mutrikuko olatu zentralaren azterketa eta potentzia maximoko puntuaren jarraipena

Susperraldian dauden energia iturri berriztagarri berriak berebiziko garrantzia izatera iritsi dira gaur egungo gizartean. Petrolioarekiko menpekotasuna eta berotegi efektua direla medio, energia lortzeko bide berriak miatu beharra nabarmendu da. Ozeanoek eta itsasoek energia kantite handia pilatzen dute bere baitan. Hala ere, gizakia oraindik ez da gai izan energia honetaz egokiro baliatzeko. Ur-zutabe oszilatzailean oinarritutako metodoa da gaur egun itsasotik energia ateratzeko sistema guztien artetik gehien ikertuenetako bat. Alabaina, lorturiko efizientzia baxuek zaildu egiten dute teknologia honen erabilera. Gaur egungo kontrol-metodo berriek, aldiz, efizientzia hau hobetzea ahalbidetzen dute. Metodo hauen artean badago potentzia maximoko puntuaren jarraipena, batez ere energia eolikoan asko erabilia.