A Remotely Controlled Sea Level Compensation System for Wave Energy Converters

Johan Abrahamsson,Rafael Waters,Mohd Nasir Ayob,Valeria Castellucci

doi:10.3390/en12101946

Johan Abrahamsson, Rafael Waters + Show 2 more

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https://doi.org/10.3390/en12101946

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Journal: Energies	Publication Date: May 21, 2019
Citations: 2	License type: CC BY 4.0

Affiliation: Universiti Malaysia Perlis

Abstract

The working principle of the wave energy converter (WEC) developed at Uppsala University (UU) is based on a heaving point absorber with a linear generator. The generator is placed on the seafloor and is connected via a steel wire to a buoy floating on the surface of the sea. The generator produces optimal power when the translator's oscillations are centered with respect to the stator. However, due to the tides or other changes in sea level, the translator's oscillations may shift towards the upper or lower limit of the generator's stroke length, resulting in a limited stroke and a consequent reduction in power production. A compensator has been designed and developed in order to keep the generator's translator centered, thus compensating for sea level variations. This paper presents experimental tests of the compensator in a lab environment. The wire adjustments are based on online sea level data obtained from the Swedish Meteorological and Hydrological Institute (SMHI). The objective of the study was to evaluate and optimize the control and communication system of the device. As the device will be self-powered with solar and wave energy, the paper also includes estimations of the power consumption and a control strategy to minimize the energy requirements of the whole system. The application of the device in a location with high tides, such as Wave Hub, was analyzed based on offline tidal data. The results show that the compensator can minimize the negative effects of sea level variations on the power production at the WEC. Although the wave energy concept of UU is used in this study, the developed system is also applicable to other WECs for which the line length between seabed and surface needs to be adjusted.

Highlights

IntroductionResearch on the production of electrical energy from ocean waves has evolved significantly over the years, with the development and testing of various types of wave energy converters (WECs)
Research on the production of electrical energy from ocean waves has evolved significantly over the years, with the development and testing of various types of wave energy converters (WECs).Different techniques and strategies have been implemented in order to improve the performance of WECs both at the simulation and theoretical level [1,2,3,4] and at the sea testing level [5,6,7]
This paper focuses on the next-generation tidal compensator for Uppsala University WECs

Summary

Introduction

Research on the production of electrical energy from ocean waves has evolved significantly over the years, with the development and testing of various types of wave energy converters (WECs). Different techniques and strategies have been implemented in order to improve the performance of WECs both at the simulation and theoretical level [1,2,3,4] and at the sea testing level [5,6,7]. At Uppsala University, the studied and developed WEC is a heaving-point-absorbing-type converter. The first version of the sea level compensator from Uppsala University, which was dimensioned for the climate of the Swedish west coast, has been tested [11]. The result from the study showed that the implementation of the compensator significantly improved energy production

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