scholarly journals Simple Controllers for Wave Energy Devices Compared

2020 ◽  
Vol 8 (10) ◽  
pp. 793
Author(s):  
Demián García-Violini ◽  
Nicolás Faedo ◽  
Fernando Jaramillo-Lopez ◽  
John V. Ringwood
Keyword(s):  
Wave Energy ◽  
Pid Controller ◽  
High Performance ◽  
Impedance Matching ◽  
Computational Cost ◽  
Numerical Algorithms ◽  
Control Engineering ◽  
Physical Constraints ◽  
Energy Devices

The design of controllers for wave energy devices has evolved from early monochromatic impedance-matching methods to complex numerical algorithms that can handle panchromatic seas, constraints, and nonlinearity. However, the potential high performance of such numerical controller comes at a computational cost, with some algorithms struggling to implement in real-time, and issues surround convergence of numerical optimisers. Within the broader area of control engineering, practitioners have always displayed a fondness for simple and intuitive controllers, as evidenced by the continued popularity of the ubiquitous PID controller. Recently, a number of energy-maximising wave energy controllers have been developed based on relatively simple strategies, stemming from the fundamentals behind impedance-matching. This paper documents this set of (5) controllers, which have been developed over the period 2010–2020, and compares and contrasts their characteristics, in terms of energy-maximising performance, the handling of physical constraints, and computational complexity. The comparison is carried out both analytically and numerically, including a detailed case study, when considering a state-of-the-art CorPower-like device.

scholarly journals CRONE control system design toolbox for the control engineering community: tutorial and case study

2013 ◽  
Vol 371 (1990) ◽  
pp. 20120149 ◽  
Author(s):  
Patrick Lanusse ◽  
Rachid Malti ◽  
Pierre Melchior
Keyword(s):  
Control System ◽  
System Design ◽  
Fractional Order ◽  
High Performance ◽  
Degrees Of Freedom ◽  
Control System Design ◽  
Robust Controllers ◽  
Control Engineering ◽  
Crone Control

Fractional-order differentiation offers new degrees of freedom that simplify the design of high-performance dynamic controllers. The CRONE control system design (CSD) methodology proposes the design of robust controllers by using fractional-order operators. A software toolbox has been developed based on this methodology and is freely available for the international scientific and industrial communities. This paper presents both the CRONE CSD methodology and its implementation using the toolbox. The design of two robust controllers for irrigation canals shows how to use the toolbox.

Optimizing the Performance of a Dual Coaxial-Cylinder Wave-Energy Extractor

2015 ◽  
Author(s):  
Daewoong Son ◽  
Valentin Belissen ◽  
Ronald W. Yeung
Keyword(s):  
Conversion Efficiency ◽  
Wave Energy ◽  
High Performance ◽  
Impedance Matching ◽  
Fold Increase ◽  
Energy Conversion Efficiency ◽  
Coaxial Cylinder ◽  
Operating Conditions ◽  
Flat Bottom ◽  
Previous Design

This study evaluates two significant design modifications of a dual coaxial-cylinder system as a wave-energy extractor reported in Son and Yeung (2014, OMAE2014-#24582). First, a new and stronger power take-off (PTO) unit for a permanent magnet linear generator (PMLG) was built, along with an appropriate supporting structure, so as to match optimality conditions in terms of impedance matching and mechanical to electrical conversion efficiency. Based on a series of (dry-)bench tests, the properties of the PTO were obtained and the optimal operating conditions were determined. Second, the flat-bottom shape of the outer toroidal floater was modified according to “The Berkeley Wedge design” (Madhi et al, 2014, “The Berkeley Wedge: an asymmetrical energy-capturing floating breakwater of high performance,” Journal of Marine Systems and Ocean Technology, vol. 9(1), pp. 5–16). The new bottom shape led to reduction of the floater damping by almost 70%, which yielded a 3-fold increase in the floater motion response. Experiments in a wave-tank validated the response behavior of the dual-cylinder system with the use of the new PTO. The Berkeley-Wedge shape allowed more than 3 times more energy be extracted compared to the flat-bottom geometry, while the new generator also improved the energy conversion efficiency. As a result, the overall system efficiency of the device was enhanced remarkably five times over that of the previous design.

scholarly journals Hydrodynamic Analysis of Surge-Type Wave Energy Devices in Variable Bathymetry by Means of BEM

Fluids ◽  
2020 ◽  
Vol 5 (2) ◽  
pp. 99 ◽  
Author(s):  
Alexandros Magkouris ◽  
Markos Bonovas ◽  
Kostas Belibassakis
Keyword(s):  
Wave Energy ◽  
Water Waves ◽  
Energy Converter ◽  
Energy Potential ◽  
Hydrodynamic Analysis ◽  
Energy Devices ◽  
Type Wave ◽  
Point Absorbers ◽  
Incident Waves

A variety of devices and concepts have been proposed and thoroughly investigated for the exploitation of renewable wave energy. Many of the devices operate in nearshore and coastal regions, and thus, variable bathymetry could have significant effects on their performance. In particular, Oscillating Wave Surge Converters (OWSCs) exploit the horizontal motion of water waves interacting with the flap of the device. In this work, a Boundary Element Method (BEM) is developed, and applied to the investigation of variable bathymetry effects on the performance of a simplified 2D model of a surge-type wave energy converter excited by harmonic incident waves. Numerical results, illustrating the effects of depth variation in conjunction with other parameters, like inertia and power-take-off, on the performance of the device, are presented. Finally, a comparative evaluation of the present simplified surge-type WEC model and point absorbers is presented for a case study in a selected coastal site on the Greek nearshore area, characterized by relatively increased wave energy potential.

Nonlinear Analysis of an Oscillating Wave Surge Converter in Frequency Domain via Statistical Linearization

2020 ◽  
Author(s):  
Leandro S. P. da Silva ◽  
Nataliia Y. Sergiienko ◽  
Benjamin S. Cazzolato ◽  
Boyin Ding ◽  
Celso P. Pesce ◽  
...  
Keyword(s):  
Nonlinear Analysis ◽  
Frequency Domain ◽  
Wave Energy ◽  
Numerical Models ◽  
Computational Cost ◽  
Viscous Drag ◽  
Design Parameters ◽  
Statistical Linearization ◽  
Mean Power ◽  
Energy Devices

Abstract Wave energy devices operate in resonant conditions to optimize power absorption, which leads to large displacements. As a result, nonlinearities play an important role in the system dynamics and must be accounted for in the numerical models for realistic prediction of the power generated. In general, time domain (TD) simulations are employed to capture the effects of the nonlinearities. However, the computational cost associated with these simulations is considerably higher compared to linear frequency domain (FD) methods. In this regard, the following work deals with the nonlinear analysis of an oscillating wave surge converter (OWSC) in the FD via the statistical linearization (SL) technique. Four nonlinearities for the proposed device are addressed: Coulomb-like torque regulated by the direction of motion, viscous drag torque, nonlinear buoyant net torque, and parametric excitation torque modulated by the flap angle. The reliability of the SL technique is compared with nonlinear TD simulations in terms of response probability distribution and power spectrum density (PSD) of the response and torque; and mean power produced. The results have demonstrated a good agreement between TD simulations and SL, while the computation time of the SL model is approximately 3 orders of magnitude faster. As a result, SL is a valuable tool to assess the OWSC performance under various wave scenarios over a range of design parameters, and can assist the development of such wave energy converters (WECs).

A Flexible Seafloor Carpet for High-Performance Wave Energy Extraction

2012 ◽  
Author(s):  
Mohammad-Reza Alam
Keyword(s):  
Wave Energy ◽  
High Performance ◽  
High Efficiency ◽  
Storm Surges ◽  
Energy Extraction ◽  
Energy Devices ◽  
Ocean Wave Energy ◽  
Ocean Renewable Energy ◽  
High Fraction ◽  
Extraction Scheme

Similar to the mechanism by which a visco-elastic mud damps the energy of overpassing surface waves, if the near-shore seafloor is carpeted by an elastic thin material attached to generators (i.e. dampers) a high fraction of surface wave energy can be absorbed. Here we present analytical modeling of the flexible carpet wave energy converter and show that a high efficiency is achievable. Expressions for optimal damping and stiffness coefficients are derived and different modes of oscillations are discussed. The presented wave energy conversion scheme is completely under the water surface hence imposes minimal danger to boats and the sea life (i.e. no mammal entanglement). The carpet is survivable against high momentum of storm surges and in fact can perform well under very energetic (e.g. stormy) sea conditions, when most existing wave energy devices are needed to shelter themselves by going into an idle mode. I am honored to be a colleague of Prof. Ronald Yeung at the University of California, Berkeley. He is a world renowned scientist of ship hydrodynamics with several valuable and key contributions to the field. This manuscript on a new ocean wave energy extraction scheme is due to Ron’s recent interest in the field of ocean renewable energy. I am looking forward to years of working closely with him. Thank you Ron.

scholarly journals A practical approach to wave energy modeling and control

2020 ◽  
Author(s):  
Ryan G. Coe ◽  
Giorgio Bacelli ◽  
Dominic Forbush
Keyword(s):  
Wave Energy ◽  
Impedance Matching ◽  
Control Design ◽  
Dynamics Modeling ◽  
Control Logic ◽  
Modeling And Control ◽  
Energy Devices ◽  
Fm Radio ◽  
The Cost ◽  
And Control

The potential for control design to dramatically improve the economic viability of wave energy has generated a great deal of interest and excitement. However, for a number of reasons, the promised benefits from better control designs have yet to be widely realized by wave energy devices and wave energy remains a relatively nascent technology. This brief paper summarizes a simple, yet powerful approach to wave energy dynamics modeling, and subsequent control design based on impedance matching. Our approach leverages the same concepts that are exploited by a simple FM radio to achieve a feedback controller for wave energy devices that approaches optimal power absorption. If fully utilized, this approach can deliver immediate and consequential reductions to the cost of wave energy. Additionally, this approach provides the necessary framework for control co-design of a WEC, in which an understanding of the control logic allows for synchronous design of the device control system and hardware.

scholarly journals Low-Cost Unattended Design of Miniaturized 4 × 4 Butler Matrices with Nonstandard Phase Differences

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 851
Author(s):  
Adrian Bekasiewicz ◽  
Slawomir Koziel
Keyword(s):  
High Performance ◽  
Low Cost ◽  
Computational Cost ◽  
Numerical Algorithms ◽  
Building Blocks ◽  
Mobile Systems ◽  
Fine Tuning ◽  
Control Synthesis ◽  
Primary Concern ◽  
Phase Differences

Design of Butler matrices dedicated to Internet of Things and 5th generation (5G) mobile systems—where small size and high performance are of primary concern—is a challenging task that often exceeds capabilities of conventional techniques. Lack of appropriate, unified design approaches is a serious bottleneck for the development of Butler structures for contemporary applications. In this work, a low-cost bottom-up procedure for rigorous and unattended design of miniaturized 4 × 4 Butler matrices is proposed. The presented approach exploits numerical algorithms (governed by a set of suitable objective functions) to control synthesis, implementation, optimization, and fine-tuning of the structure and its individual building blocks. The framework is demonstrated using two miniaturized matrices with nonstandard output-port phase differences. Numerical results indicate that the computational cost of the design process using the presented framework is over 80% lower compared to the conventional approach. The footprints of optimized matrices are only 696 and 767 mm2, respectively. Small size and operation frequency of around 2.6 GHz make the circuits of potential use for mobile devices dedicated to work within a sub-6 GHz 5G spectrum. Both structures have been benchmarked against the state-of-the-art designs from the literature in terms of performance and size. Measurements of the fabricated Butler matrix prototype are also provided.

scholarly journals The physics of numerical analysis: a climate modelling case study

2020 ◽  
Vol 378 (2166) ◽  
pp. 20190058 ◽  
Author(s):  
T. N. Palmer
Keyword(s):  
Numerical Analysis ◽  
Computer Science ◽  
High Performance ◽  
Numerical Algorithms ◽  
Climate Science ◽  
Computational Science ◽  
Climate Modelling

The case is made for a much closer synergy between climate science, numerical analysis and computer science. This article is part of a discussion meeting issue ‘Numerical algorithms for high-performance computational science’.

scholarly journals A practical approach to wave energy modeling and control

2020 ◽  
Author(s):  
Ryan G. Coe ◽  
Giorgio Bacelli ◽  
Dominic Forbush
Keyword(s):  
Wave Energy ◽  
Impedance Matching ◽  
Control Design ◽  
Dynamics Modeling ◽  
Control Logic ◽  
Modeling And Control ◽  
Energy Devices ◽  
Fm Radio ◽  
The Cost ◽  
And Control

The potential for control design to dramatically improve the economic viability of wave energy has generated a great deal of interest and excitement. However, for a number of reasons, the promised benefits from better control designs have yet to be widely realized by wave energy devices and wave energy remains a relatively nascent technology. This brief paper summarizes a simple, yet powerful approach to wave energy dynamics modeling, and subsequent control design based on impedance matching. Our approach leverages the same concepts that are exploited by a simple FM radio to achieve a feedback controller for wave energy devices that approaches optimal power absorption. If fully utilized, this approach can deliver immediate and consequential reductions to the cost of wave energy. Additionally, this approach provides the necessary framework for control co-design of a WEC, in which an understanding of the control logic allows for synchronous design of the device control system and hardware.

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