Spring-resonance-assisted maximal power tracking control of a direct-drive wave energy converter

2021 ◽  
pp. 014233122110132
Author(s):  
Ning Wang ◽  
Yusen Jia ◽  
Shui Fu
Keyword(s):  
Wave Energy ◽  
Tracking Control ◽  
Sliding Mode ◽  
Wave Energy Converter ◽  
Direct Drive ◽  
Maximal Power ◽  
Energy Converter ◽  
System A ◽  
Control Framework ◽  
Fast Adaptation

In this paper, to finely accommodate large-range wave frequencies on same sea areas, a spring resonance mechanism is created to facilitate maximal power tracking control of a direct-drive wave energy converter (DWEC) that is expected to be equipped on same sea areas, whereby the spring-resonance-assisted module is devised by mover-coaxial springs and reshapes the resonant-frequency pertaining to a specific spectrum. By virtue of modeling the spring-resonance-assisted DWEC system, a finite-time disturbance observer (FDO) is deployed to rapidly compensate environmental disturbances. Accordingly, the FDO-based integral sliding-mode (ISM) control framework is proposed, to accurately achieve the resonance between the DWEC buoy and wave, thereby contributing to spring-resonance-assisted maximal power tracking control (SR-MPTC) of the DWEC. Simulation studies and comprehensive comparisons demonstrate that the proposed SR-MPTC scheme performs remarkably fast adaptation and accurately maximal power tracking in the presence of disturbances and spring resonance assistance.

Power Conditioning Unit for Direct-Drive Wave Energy Converter

2018 ◽  
Author(s):  
Yuriy Rozanov ◽  
Konstantin Kryukov ◽  
Mikhail Kiselev ◽  
Mikhail Lepanov ◽  
Yuriy Tserkovsky ◽  
...  
Keyword(s):  
Wave Energy ◽  
Wave Energy Converter ◽  
Direct Drive ◽  
Power Conditioning ◽  
Energy Converter

scholarly journals Analysis, design and testing of a novel direct‐drive wave energy converter system

2013 ◽  
Vol 7 (5) ◽  
pp. 565-573 ◽  
Author(s):  
Richard Crozier ◽  
Helen Bailey ◽  
Markus Mueller ◽  
Edward Spooner ◽  
Paul McKeever
Keyword(s):  
Wave Energy ◽  
Wave Energy Converter ◽  
Direct Drive ◽  
Energy Converter ◽  
Analysis Design ◽  
Design And Testing

Influence of Generator Damping on Peak Power and Variance of Power for a Direct Drive Wave Energy Converter

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Magnus Stålberg ◽  
Rafael Waters ◽  
Oskar Danielsson ◽  
Mats Leijon
Keyword(s):  
Wave Energy ◽  
Peak Power ◽  
Load Resistance ◽  
Wave Energy Converter ◽  
Damping Factor ◽  
Direct Drive ◽  
Energy Converter ◽  
Swedish West Coast ◽  
Electric System ◽  
Point Absorber

The first offshore prototype of a wave energy converter system has been launched off the Swedish west coast. The concept is based on a point absorber directly coupled to a linear generator located on the ocean floor. The wave energy converter is part of a research project that will study the electric system of ten units forming a small farm of wave power plants as they are linked and connected to an electric grid. A full scale farm will consist of a large number of interconnected units. The chosen direct drive system reduces the mechanical complexity of the converter but has repercussions on the electric system. The output from the generator will vary with the speed of the point absorber, leading to large fluctuations of power on the second scale. This has implications on both the individual generator and on the system as a whole. The hydrodynamic behavior of the point absorber depends, to a large extent, on the damping of the generator. The damping, in turn, can be remotely controlled by changing the load resistance. It has previously been shown that this has a large influence on the power absorbed by the wave energy converter. This paper investigates the peak power, the translator speed, and the variance of the power at different sea states and for different levels of damping. The peak power has an impact on the design of the generator and the required ability, for a single unit, to handle electric overloads. The momentum of the translator is directly proportional to its speed. The speed is thus important for the design of the end stop. The variance of the power of one unit will have an impact on the farm system behavior. The study is based on two and a half months of experimental measurements on the prototype wave energy converter and a wave measurement buoy. The aim is to analyze whether load control strategies may influence the dimensioning criteria for the electric system and the generator. The results are compared to previously investigated relationships between the absorbed mean power and the load resistance as a function of sea state. In the study, it was found that the maximum power is approximately proportional to the average power, while the maximum translator speed and standard deviation decrease as the damping factor is increased.

scholarly journals Performance analysis of a point-absorber wave energy converter with a single buoy composed of three rigidly coupled structures

2021 ◽  
Vol 4 (2) ◽  
pp. 37-45
Author(s):  
Aldo Ruezga ◽  
José M. Cañedo C. ◽  
Manuel G. Verduzco-Zapata ◽  
Francisco J. Ocampo-Torres
Keyword(s):  
Wave Energy ◽  
Wave Energy Converter ◽  
Floating Body ◽  
Analysis Tool ◽  
Direct Drive ◽  
Energy Converter ◽  
Drive Power ◽  
Point Absorber ◽  
Single Body ◽  
Coupled Structures

A single-body point absorber system is analysed to improve its power absorption at a finite water depth.  The proposed wave energy converter consists of a single floating body coupled to a direct-drive power take-off system placed on the seabed. The structure of a cylindrical buoy with large draft is changed by a single body composed of three structures rigidly coupled, reducing its volume and improving its frequency-dependent hydrostatic parameters that are obtained through a numerical analysis tool called NEMOH. The undamped natural frequency of the oscillating system is tuned to a specified wave period and the performance of the WEC system is obtained assuming a linear Power Take-Off system. In time domain, the performance of the WEC device is carried-out under a regular (sinusoidal) and irregular incident wave profile. Comparing the performance of the WEC system using the cylindrical and the proposed buoy outcomes that the system with the proposed buoy is able to absorb more energy from incident waves with a wider frequency range, whereas the oscillating system is kept as simple as possible.

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