scholarly journals Control Strategies Applied to Wave Energy Converters: State of the Art

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3115 ◽  
Author(s):  
Aleix Maria-Arenas ◽  
Aitor J. Garrido ◽  
Eugen Rusu ◽  
Izaskun Garrido

Wave energy’s path towards commercialization requires maximizing reliability, survivability, an improvement in energy harvested from the wave and efficiency of the wave to wire conversion. In this sense, control strategies directly impact the survivability and safe operation of the device, as well as the ability to harness the energy from the wave. For example, tuning the device’s natural frequency to the incoming wave allows resonance mode operation and amplifies the velocity, which has a quadratic proportionality to the extracted energy. In this article, a review of the main control strategies applied in wave energy conversion is presented along their corresponding power take-off (PTO) systems.

Author(s):  
Hoai-Nam Nguyen ◽  
Guillaume Sabiron ◽  
Paolino Tona ◽  
Morten Mejlhede Kramer ◽  
Enrique Vidal Sanchez

One of the major limitations to the development of advanced wave energy converters (WECs) control strategies are the associated computational costs. For instance, model predictive control (MPC) strategies have the potential to obtain almost optimal performance, provided that the imperfect power conversion in the power take-off (PTO) system is correctly taken into account in the optimization criterion and that the incoming wave force can be estimated and forecast. However, demanding computational requirements as well as the unresolved issue of wave force estimation have so far prevented real-time implementation and validation of such MPC strategies. In this paper, we present the successful experimental results obtained on a scaled-down prototype of the well-known Wavestar machine. Performance comparisons are provided for nonlinear MPC versus a reference PI controller.


Author(s):  
Wanan Sheng ◽  
Ray Alcorn ◽  
Tony Lewis

Oscillating water column (OWC) wave energy converters (WECs) are probably the simplest and most promising wave energy converters due to their good feasibility, reliability and survivability in practical wave energy conversions and also regarded as the most studied and developed when compared to other types of the wave energy converters. This research aims to develop a reliable numerical tool to assess the performance of the OWC wave energy converters, particularly in the primary wave energy conversion. In the numerical assessment tool, the hydrodynamics of the device and thermodynamics of the air chamber can be studied separately. However, for the complete dynamic system when a power takeoff (PTO) system is applied, these two dynamic systems are fully coupled in time-domain, in which the PTO can have a simple mathematical expression as the relation between the pressure difference across the PTO (the chamber pressure) and its flowrate through the PTO. And the application of a simple PTO pressure-flowrate relation very much simplifies the complicated aerodynamics and thermodynamics in the air turbine system so the whole dynamic system can be simplified. The methodology has been applied to a generic OWC device and the simulation results have been compared to the experimental data. It is shown that the developed numerical method is reliable in and capable of assessing the primary wave energy conversion of oscillating water columns.


Author(s):  
Zhenwei Liu ◽  
Ran Zhang ◽  
Han Xiao ◽  
Xu Wang

Ocean wave energy conversion as one of the renewable clean energy sources is attracting the research interests of many people. This review introduces different types of power take-off technology of wave energy converters. The main focus is the linear direct drive power take-off devices as they have the advantages for ocean wave energy conversion. The designs and optimizations of power take-off systems of ocean wave energy converters have been studied from reviewing the recently published literature. Also, the simple hydrodynamics of wave energy converters have been reviewed for design optimization of the wave energy converters at specific wave sites. The novel mechanical designs of the power take-off systems have been compared and investigated in order to increase the energy harvesting efficiency.


Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1665
Author(s):  
Aleix Maria-Arenas ◽  
Aitor J. Garrido ◽  
Eugen Rusu ◽  
Izaskun Garrido

The authors would like to add the following note to Figure 7 of their paper published in Energies [...]


Author(s):  
DIGVIJAY SINGH RAGHUVANSHI ◽  
JAYESH L. MINASE

Ocean waves, if employed efficiently for generation of electricity, could result in the most economic green process (minimal carbon emission). This paper, based on the extensive literature survey conducted as a part of a B.Tech Project provides an overview of the current scenario of power generation and consumption in India thereby emphasizing on the progressively increasing power requirement and a lagging behind share of renewable energy. A scientific clarity is drawn on the basic theory behind wave generation and the key factors for assessing and deploying wave energy converters. Further, a few successful wave energy conversion techniques are discussed briefly, which posses the potential scope of future research and development and are presently employed under pre-commercial and commercial stages around the globe. A special emphasis is laid on the point absorber section which has been the area of research for the authors‘ project thereby detailing its constructional and working aspects and also discussing briefly an experimental procedure to set up a wave generator, to calculate mechanical conversion efficiency, and its scope of applicability. The conclusion is drawn in favor of the coastal communities which still rely on costly diesel for generating electricity.


Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6537
Author(s):  
Emiliano Renzi ◽  
Simone Michele ◽  
Siming Zheng ◽  
Siya Jin ◽  
Deborah Greaves

We review wave energy conversion technologies for niche applications, i.e., kilowatt-scale systems that allow for more agile design, faster deployment and easier operation than utility scale systems. The wave energy converters for niche markets analysed in this paper are classified into breakwater-integrated, hybrid, devices for special applications. We show that niche markets are emerging as a very vibrant landscape, with several such technologies having now achieved operational stage, and others undergoing full-scale sea trials. This review also includes flexible devices, which started as niche applications in the 1980s and are now close to commercial maturity. We discuss the strong potential of flexible devices in reducing costs and improving survivability and reliability of wave energy systems. Finally, we show that the use of WECs in niche applications is supporting the development of utility-scale projects by accumulating field experience, demonstrating success stories of grid integration and building confidence for stakeholders.


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