A New Bi-Level Optimisation Framework for Optimising a Multi-Mode Wave Energy Converter Design: A Case Study for the Marettimo Island, Mediterranean Sea

To advance commercialisation of ocean wave energy and for the technology to become competitive with other sources of renewable energy, the cost of wave energy harvesting should be significantly reduced. The Mediterranean Sea is a region with a relatively low wave energy potential, but due to the abs...

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Main Authors: Mehdi Neshat, Nataliia Y. Sergiienko, Erfan Amini, Meysam Majidi Nezhad, Davide Astiaso Garcia, Bradley Alexander, Markus Wagner
Format: Article
Language:English
Published: MDPI AG 2020-10-01
Series:Energies
Subjects:
Online Access:https://www.mdpi.com/1996-1073/13/20/5498
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spelling doaj-1a449a521d6b4db28a8b86852e026ba22020-11-25T03:33:56ZengMDPI AGEnergies1996-10732020-10-01135498549810.3390/en13205498A New Bi-Level Optimisation Framework for Optimising a Multi-Mode Wave Energy Converter Design: A Case Study for the Marettimo Island, Mediterranean SeaMehdi Neshat0Nataliia Y. Sergiienko1Erfan Amini2Meysam Majidi Nezhad3Davide Astiaso Garcia4Bradley Alexander5Markus Wagner6Optimization and Logistics Group, School of Computer Science, The University of Adelaide, 5005 Adelaide, AustraliaSchool of Mechanical Engineering, The University of Adelaide, 5005 Adelaide, AustraliaCoastal and offshore structures engineering group, School of Civil Engineering, University of Tehran, 13145-1384 Tehran, IranDepartment of Astronautics, Electrical and Energy Engineering (DIAEE), Sapienza University of Rome, 00184 Rome, ItalyDepartment of Planning, Design and Technology of Architecture, Sapienza University of Rome, 00197 Rome, ItalyOptimization and Logistics Group, School of Computer Science, The University of Adelaide, 5005 Adelaide, AustraliaOptimization and Logistics Group, School of Computer Science, The University of Adelaide, 5005 Adelaide, AustraliaTo advance commercialisation of ocean wave energy and for the technology to become competitive with other sources of renewable energy, the cost of wave energy harvesting should be significantly reduced. The Mediterranean Sea is a region with a relatively low wave energy potential, but due to the absence of extreme waves, can be considered at the initial stage of the prototype development as a proof of concept. In this study, we focus on the optimisation of a multi-mode wave energy converter inspired by the CETO system to be tested in the west of Sicily, Italy. We develop a computationally efficient spectral-domain model that fully captures the nonlinear dynamics of a wave energy converter (WEC). We consider two different objective functions for the purpose of optimising a WEC: (1) maximise the annual average power output (with no concern for WEC cost), and (2) minimise the levelised cost of energy (LCoE). We develop a new bi-level optimisation framework to simultaneously optimise the WEC geometry, tether angles and power take-off (PTO) parameters. In the upper-level of this bi-level process, all WEC parameters are optimised using a state-of-the-art self-adaptive differential evolution method as a global optimisation technique. At the lower-level, we apply a local downhill search method to optimise the geometry and tether angles settings in two independent steps. We evaluate and compare the performance of the new bi-level optimisation framework with seven well-known evolutionary and swarm optimisation methods using the same computational budget. The simulation results demonstrate that the bi-level method converges faster than other methods to a better configuration in terms of both absorbed power and the levelised cost of energy. The optimisation results confirm that if we focus on minimising the produced energy cost at the given location, the best-found WEC dimension is that of a small WEC with a radius of 5 m and height of 2 m.https://www.mdpi.com/1996-1073/13/20/5498bi-level optimisation methodevolutionary algorithmsrenewable energywave energy convertergeometric parameterspower take-off
collection DOAJ
language English
format Article
sources DOAJ
author Mehdi Neshat
Nataliia Y. Sergiienko
Erfan Amini
Meysam Majidi Nezhad
Davide Astiaso Garcia
Bradley Alexander
Markus Wagner
spellingShingle Mehdi Neshat
Nataliia Y. Sergiienko
Erfan Amini
Meysam Majidi Nezhad
Davide Astiaso Garcia
Bradley Alexander
Markus Wagner
A New Bi-Level Optimisation Framework for Optimising a Multi-Mode Wave Energy Converter Design: A Case Study for the Marettimo Island, Mediterranean Sea
Energies
bi-level optimisation method
evolutionary algorithms
renewable energy
wave energy converter
geometric parameters
power take-off
author_facet Mehdi Neshat
Nataliia Y. Sergiienko
Erfan Amini
Meysam Majidi Nezhad
Davide Astiaso Garcia
Bradley Alexander
Markus Wagner
author_sort Mehdi Neshat
title A New Bi-Level Optimisation Framework for Optimising a Multi-Mode Wave Energy Converter Design: A Case Study for the Marettimo Island, Mediterranean Sea
title_short A New Bi-Level Optimisation Framework for Optimising a Multi-Mode Wave Energy Converter Design: A Case Study for the Marettimo Island, Mediterranean Sea
title_full A New Bi-Level Optimisation Framework for Optimising a Multi-Mode Wave Energy Converter Design: A Case Study for the Marettimo Island, Mediterranean Sea
title_fullStr A New Bi-Level Optimisation Framework for Optimising a Multi-Mode Wave Energy Converter Design: A Case Study for the Marettimo Island, Mediterranean Sea
title_full_unstemmed A New Bi-Level Optimisation Framework for Optimising a Multi-Mode Wave Energy Converter Design: A Case Study for the Marettimo Island, Mediterranean Sea
title_sort new bi-level optimisation framework for optimising a multi-mode wave energy converter design: a case study for the marettimo island, mediterranean sea
publisher MDPI AG
series Energies
issn 1996-1073
publishDate 2020-10-01
description To advance commercialisation of ocean wave energy and for the technology to become competitive with other sources of renewable energy, the cost of wave energy harvesting should be significantly reduced. The Mediterranean Sea is a region with a relatively low wave energy potential, but due to the absence of extreme waves, can be considered at the initial stage of the prototype development as a proof of concept. In this study, we focus on the optimisation of a multi-mode wave energy converter inspired by the CETO system to be tested in the west of Sicily, Italy. We develop a computationally efficient spectral-domain model that fully captures the nonlinear dynamics of a wave energy converter (WEC). We consider two different objective functions for the purpose of optimising a WEC: (1) maximise the annual average power output (with no concern for WEC cost), and (2) minimise the levelised cost of energy (LCoE). We develop a new bi-level optimisation framework to simultaneously optimise the WEC geometry, tether angles and power take-off (PTO) parameters. In the upper-level of this bi-level process, all WEC parameters are optimised using a state-of-the-art self-adaptive differential evolution method as a global optimisation technique. At the lower-level, we apply a local downhill search method to optimise the geometry and tether angles settings in two independent steps. We evaluate and compare the performance of the new bi-level optimisation framework with seven well-known evolutionary and swarm optimisation methods using the same computational budget. The simulation results demonstrate that the bi-level method converges faster than other methods to a better configuration in terms of both absorbed power and the levelised cost of energy. The optimisation results confirm that if we focus on minimising the produced energy cost at the given location, the best-found WEC dimension is that of a small WEC with a radius of 5 m and height of 2 m.
topic bi-level optimisation method
evolutionary algorithms
renewable energy
wave energy converter
geometric parameters
power take-off
url https://www.mdpi.com/1996-1073/13/20/5498
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