Experimental Results From an Offshore Wave Energy Converter

2008 ◽  
Author(s):  
Cecilia Bostro¨m ◽  
Erik Lejerskog ◽  
Simon Tyberg ◽  
Olle Svensson ◽  
Rafael Waters ◽  
...  
Keyword(s):  
Wave Energy ◽  
Energy System ◽  
Wave Energy Converter ◽  
Energy Converter ◽  
Swedish West Coast ◽  
Grid Connection ◽  
Linear Load ◽  
Non Linear Load ◽  
Offshore Wave ◽  
Voltage Conversion

An offshore wave energy converter (WEC) was successfully launched at the Swedish west coast in the middle of March 2006. The WEC is based on a permanent magnet linear generator located on the ocean floor driven by a point absorber. A measuring station has been installed on a nearby island where all measurements and experiments on the WEC have been carried out. The output voltage from the generator fluctuates both in amplitude and frequency and must therefore be converted to enable grid connection. In order to study the voltage conversion, the measure station was fitted with a six pulse diode rectifier and a capacitive filter during the autumn of 2006. The object of this paper is to present a detailed description of the existing wave energy system of the Islandsberg project. Special attention will be given to the power absorption by the generator when it is connected to a non linear load.

Experimental Results From an Offshore Wave Energy Converter

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Cecilia Boström ◽  
Erik Lejerskog ◽  
Simon Tyrberg ◽  
Olle Svensson ◽  
Rafael Waters ◽  
...  
Keyword(s):  
Wave Energy ◽  
Wave Energy Converter ◽  
Energy Converter ◽  
Nonlinear Load ◽  
Swedish West Coast ◽  
Point Absorber ◽  
Measuring Station ◽  
Grid Connection ◽  
Offshore Wave ◽  
Voltage Conversion

An offshore wave energy converter (WEC) was successfully launched at the Swedish west coast in the middle of March 2006. The WEC is based on a permanent magnet linear generator located on the sea floor driven by a point absorber. A measuring station has been installed on a nearby island where all measurements and experiments on the WEC have been carried out. The output voltage from the generator fluctuates both in amplitude and frequency and must therefore be converted to enable grid connection. In order to study the voltage conversion, the measuring station was fitted with a six pulse diode rectifier and a capacitive filter during the autumn of 2006. The object of this paper is to present a detailed description of the Lysekil research site. Special attention will be given to the power absorption by the generator when it is connected to a nonlinear load.

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 Numerical simulation of a wave energy converter using linear generator

2013 ◽  
Vol 35 (2) ◽  
pp. 103-111 ◽  
Author(s):  
Dang The Ba
Keyword(s):  
Numerical Simulation ◽  
Wave Energy ◽  
Energy Demand ◽  
Wave Energy Converter ◽  
Linear Potential ◽  
Energy Converter ◽  
Wave Condition ◽  
Mechanics Model ◽  
South Central ◽  
Offshore Wave

This paper presents results of numerical simulation for a wave energy converter using linear permanent magnet generator. The use of linear permanent generator has advantages of simple structure, minimizing mechanical loose... On the base of mechanics model, a system of equations describing the operation of the device under linear potential wave was obtained. The magnetic field in generator was calculated by Flex-PDE software. The system of movement equations was numerically solved with Matlab.Various calculations were performed with different parameters of wave conditions and device's structures to determine the device’s configuration for a 300 W output power for the offshore wave condition in South-Central offshore of Vietnam. The results also show potential of developing the wave energy conversion to meet the energy demand in some coastal and island regions of Vietnam.

scholarly journals The Economic Feasibility of Floating Offshore Wave Energy Farms in the North of Spain

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 806 ◽  
Author(s):  
Laura Castro-Santos ◽  
Ana Bento ◽  
Carlos Guedes Soares
Keyword(s):  
Wave Energy ◽  
Net Present Value ◽  
Energy Resource ◽  
Economic Feasibility ◽  
Wave Energy Converter ◽  
Energy Converter ◽  
The North ◽  
Cost Of Energy ◽  
Offshore Wave ◽  
North Of Spain

A technique to analyse the economic viability of offshore farms composed of wave energy converters is proposed. Firstly, the inputs, whose value will be considered afterwards in the economic step, was calculated using geographic information software. Secondly, the energy produced by each wave converter was calculated. Then the economic factors were computed. Finally, the restriction that considers the depth of the region (bathymetry) was put together with the economic outputs, whose value depends on the floating Wave Energy Converter (WEC). The method proposed was applied to the Cantabric and Atlantic coasts in the north of Spain, a region with a good offshore wave energy resource. In addition, three representative WECs were studied: Pelamis, AquaBuoy and Wave Dragon; and five options for electric tariffs were analysed. Results show the Wave Energy Converter that has the best results regarding its LCOE (Levelized Cost of Energy), IRR (Internal Rate of Return) and NPV (Net Present Value), and which area is best for the development of a wave farm.

scholarly journals A Set-Up of 7 Laser Triangulation Sensors and a Draw-Wire Sensor for Measuring Relative Displacement of a Piston Rod Mechanical Lead-Through Transmission in an Offshore Wave Energy Converter on the Ocean Floor

2012 ◽  
Vol 2012 ◽  
pp. 1-32 ◽  
Author(s):  
E. Strömstedt ◽  
O. Svensson ◽  
M. Leijon
Keyword(s):  
Energy Conversion ◽  
Measurement System ◽  
Wave Energy ◽  
Relative Displacement ◽  
Operating Conditions ◽  
Wave Energy Converter ◽  
Laser Triangulation ◽  
Energy Converter ◽  
Set Up ◽  
Offshore Wave

A concept for offshore wave energy conversion is being developed at the Swedish Centre for Renewable Electric Energy Conversion at Uppsala University in Sweden. The wave energy converter (WEC) in focus contains a piston rod mechanical lead-through transmission for transmitting the absorbed mechanical wave energy through the generator capsule wall while preventing seawater from entering the capsule. A set-up of 7 laser triangulation sensors has been installed inside the WEC to measure relative displacement of the piston rod and its corresponding seal housing. A draw-wire sensor has also been set up to measure translator position and the axial displacement of the piston rod. The paper gives a brief introduction to the Lysekil research site, the WEC concept, and the direct drive of WEC prototype L2. A model of operation for the piston rod mechanical lead-through transmission is given. The paper presents sensor choice, configuration, adaptation, mounting, and measurement system calibration along with a description of the data acquisition system. Results from 60 s measurements of nominal operation two months apart with centered moving averages are presented. Uncertainty and error estimations with statistical analyses and signal-to-noise ratios are presented. Conclusions are drawn on the relative motions of the piston rod and the seal housing under normal operating conditions, and an assessment of the applicability of the measurement system is made.

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

2007 ◽  
Author(s):  
Magnus Sta˚lberg ◽  
Rafael Waters ◽  
Oskar Danielsson ◽  
Mats Leijon
Keyword(s):  
Wave Energy ◽  
Peak Power ◽  
Load Resistance ◽  
Full Scale ◽  
Wave Energy Converter ◽  
Direct Drive ◽  
Electrical System ◽  
Energy Converter ◽  
Swedish West Coast ◽  
Point Absorber

The first full-scale offshore prototype of a novel 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 electrical system of 10 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 electrical 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 controlled remotely 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 electrical overloads. The speed of the translator is directly proportional to its momentum. It 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 electrical system and the generator. The results are compared with previously investigated relationships between absorbed mean power and 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 maximum translator speed and standard deviation decrease as the damping factor is increased.

Sign in / Sign up

Export Citation Format

Share Document