Damping Studies on PMLG-Based Wave Energy Converter under Oceanic Wave Climates

Yue Hong,Irina Temiz,Jianfei Pan,Mikael Eriksson,Cecilia Boström

doi:10.3390/en14040920

Abstract

Wave energy converters (WECs), which are designed to harvest ocean wave energy, have recently been improved by the installation of numerous conversion mechanisms; however, it is still difficult to find an appropriate method that can compromise between strong environmental impact and robust performance by transforming irregular wave energy into stable electrical power. To solve this problem, an investigation into the impact of varied wave conditions on the dynamics of WECs and to determine an optimal factor for WECs to comply with long-term impacts was performed. In this work, we researched the performance of WECs influenced by wave climates. We used a permanent magnet linear generator (PMLG)-based WEC that was invented at Uppsala University. The damping effect was first studied with a PMLG-type WEC. Then, a group of sea states was selected to investigate their impact on the power production of the WEC. Two research sites were chosen to investigate the WEC’s annual energy production as well as a study on the optimal damping coefficient impact. In addition, we compared the WEC’s energy production between optimal damping and constant damping under a full range of sea states at both sites. Our results show that there is an optimal damping coefficient that can achieve the WEC’s maximum power output. For the chosen research sites, only a few optimal damping coefficients were able to contribute over 90% of the WEC’s annual energy production. In light of the comparison between optimal and constant damping, we conclude that, for specific regions, constant damping might be a better choice for WECs to optimize long-term energy production.

Highlights

Wave energy technology was proposed as a concept for harvesting energy from ocean waves, with its first relevant patent documented in 1799 [1]
By investigating annual wave climates found at different test sites, we propose optimal choices for the damping coefficient to enhance wave energy converters (WECs) power production
Phase voltage generated from linear generator model: (a) Comparison of the phase

Summary

Introduction

Wave energy technology was proposed as a concept for harvesting energy from ocean waves, with its first relevant patent documented in 1799 [1]. Devices aiming to generate usable energy from wave energy are regarded as wave energy converters (WECs) [2]. A WEC can be divided into two major parts: One part is an absorbing component to extract energy by reacting to the waves and the other part is a generating system that transforms the absorbed mechanical energy into usable energy (mostly electrical energy). There are lists of WECs dedicated to harvesting wave energy, with a variety of designs from mechanical structure to electrical conversion. Falcao gave a comprehensive overview on the mechanical structure and control methods of WECs [3]. Penalba published a review on wave-to-wire models for wave energy converters [5]. Ozkop summarized the control methods employed in WECs [6]

Methods

Results

Conclusion