Control of Wave Energy Converter With Losses in Electrical Power Take-Off System

2021 ◽  
Author(s):  
Xiang Zhou ◽  
Shangyan Zou ◽  
Wayne W. Weaver ◽  
Ossama Abdelkhalik
Keyword(s):  
Wave Energy ◽  
Power Output ◽  
Passive Control ◽  
Reactive Power ◽  
Electrical Power ◽  
Wave Energy Converter ◽  
Electrical Machine ◽  
Linear Wave ◽  
Energy Converter ◽  
Electrical Power Output

Abstract A permanent magnet linear electrical machine power takeoff (PTO) unit is simulated on the direct drive wave energy converter in this paper, which is controlled to provide the required reactive power. A shape-based control is implemented to maximize the wave energy production (mechanical PTO) with the limiting constraints on the electric drive. Further, the linear electrical machine design is optimized such that the electrical power output is maximized (e.g., reduced power losses). The numerical simulations are conducted using MATLAB/Simulink and the Simscape toolbox. Linear wave theory is applied in modeling the buoy dynamics. Additionally, the PTO unit is composed of a linear electrical machine, an ideal inverter, and an ideal energy storage system. The results show the proposed PTO tracks the reference control accurately. The electrical power output is significantly improved by limiting the current in the PTO compared to a passive control.

Power Output Performance and Smoothing Ability of an Oscillating Water Column Array Wave Energy Converter

2013 ◽  
Author(s):  
Keith O’Sullivan ◽  
Jimmy Murphy ◽  
Dara O’Sullivan
Keyword(s):  
Time Series ◽  
Water Column ◽  
Wind Turbines ◽  
Wave Energy ◽  
Power Output ◽  
Output Signal ◽  
Electrical Power ◽  
Wave Energy Converter ◽  
Oscillating Water Column ◽  
Energy Converter

This paper presents the physical model testing results of a floating oscillating water column (OWC) array wave energy converter (WEC) and the power smoothing ability inherent in the OWC chamber arrangement in the structure. The device can be categorised as a very large floating structure (VLFS) with structure dynamics which may make it a suitable device on which to mount wind turbines. It incorporates 32 individual OWC chambers in a “V” shaped arrangement such that there is a phase-lag between successive wave crests in the OWC chambers as an individual wave passes the structure. This OWC array was tested in both monochromatic and panchromatic unidirectional wave fields and the motion response amplitude operators (RAO) have been calculated. The time series of absorbed power from panchromatic waves was then used as input to a simple Well’s turbine power take-off (PTO) Simulink model to estimate the electrical power produced by each chamber and the additive power produced by the 32 OWC’s. A simple control law of optimum speed of the generator was used for these simulations. The time series of total electrical power from the 32 chambers was compared to the time series of an individual chamber and the standard deviation of the signals were also compared. The OWC array achieved a much smoother power output signal than a device with one chamber. Further smoothing of the output signal is possible by increasing the inertia of the turbine however, this may have implications for the mean efficiency of the power train. A preliminary design of the Well’s turbine is included, both in terms of mechanical parts and generator rating. This paper focusses on the power absorption and motion performance of the device and discusses the potential for the addition of wind turbines.

Numerical Study on Expected Electrical Power of Linear Wave Energy Converter in Arrangement Condition

2017 ◽  
Author(s):  
Qiao Li ◽  
Motohiko Murai ◽  
Syu Kuwada
Keyword(s):  
Wave Energy ◽  
Numerical Study ◽  
Mechanical Energy ◽  
Electrical Power ◽  
Wave Energy Converter ◽  
Linear Wave ◽  
Energy Converter ◽  
Multiple Wave ◽  
Floating Structures ◽  
Electrical Generator

A linear electrical generator is a kind of device which can be used to wave energy converter, for directly converting mechanical energy of a floating structure into electrical energy. A wave farm consists of multiple wave energy converters which equipped in a sea area. In the present paper, a numerical model is proposed considering the interference effect in the multiple floating structures, and the controlling force of each linear electrical generator. Especially, the copper losses in the electrical generator is taken into account, when the electrical power is computed. At first, the controlling force coefficients are discussed to find their physical effects on heaving motion. In a case study, the heaving motions and electrical powers of the three floating structures are estimated in the straight arrangement and triangle arrangement. And the average electrical power is analyzed in different distances of the floating structures.

Numerical Simulation of Duck Wave Energy Converter

2016 ◽  
Vol 693 ◽  
pp. 484-490
Author(s):  
Ying Xue Yao ◽  
Hai Long Li ◽  
Jin Ming Wu ◽  
Liang Zhou
Keyword(s):  
Numerical Simulation ◽  
Wave Energy ◽  
Pitch Angle ◽  
Low Cost ◽  
Three Dimensional ◽  
Angular Frequency ◽  
Wave Energy Converter ◽  
Linear Wave ◽  
Energy Converter ◽  
Flow Theories

Duck wave energy converter has the advantages of high conversion efficiency, simple construction, low cost relative to other wave power device. In the paper, the numerical simulation of the response of the converter was calculated by the AQWA software which based on the three dimensional potential flow theories. The results show that the pitch angle appear the peak when the incident wave frequency is 1rad/s and the maximum of the pitch angle come out as the linear wave normally incident the duck body, which means duck wave energy converter can absorb more wave energy in this angular frequency. The above research can provide reference for the design of the duck wave energy converter.

A Joint Numerical and Experimental Study of a Surging Point Absorbing Wave Energy Converter (WRASPA)

2009 ◽  
Author(s):  
Majid A. Bhinder ◽  
Clive G. Mingham ◽  
Derek M. Causon ◽  
Mohammad T. Rahmati ◽  
George A. Aggidis ◽  
...  
Keyword(s):  
Wave Energy ◽  
Informed Choice ◽  
Wave Energy Converter ◽  
Body Motion ◽  
Numerical Dissipation ◽  
Small Scale ◽  
Linear Wave ◽  
Energy Converter ◽  
Non Linear ◽  
Experimental Project

This paper presents the findings from using several commercial computational fluid dynamics codes in a joint numerical and experimental project to simulate WRASPA, a new wave energy converter (WEC) device. A series of fully 3D non-linear simulations of WRASPA are presented. Three commercial codes STAR-CCM, CFX and FLOW-3D are considered for simulating the WRASPA device and final results are presented based on the use of Flow-3D. Results are validated by comparison to experimental data obtained from small scale tank tests undertaken at Lancaster University (LU). The primary aim of the project is to use numerical simulation to optimize the collector geometry for power production over a range of likely wave climates. A secondary aim is to evaluate the ability of commercial codes to simulate rigid body motion in linear and non-linear wave climates in order to choose the optimal code with respect to compute speed and ease of problem setup. Issues relating to the ability of a code in terms of numerical dissipation of waves, wave absorption, wave breaking, grid generation and moving bodies will all be discussed. The findings of this paper serve as a basis for an informed choice of commercial package for such simulations. However the capability of these commercial codes is increasing with every new release.

Preliminary laboratorial determination of the REEFS novel wave energy converter power output

2018 ◽  
Vol 122 ◽  
pp. 654-664 ◽  
Author(s):  
J.P.P.G. Lopes de Almeida ◽  
B. Mujtaba ◽  
A.M. Oliveira Fernandes
Keyword(s):  
Wave Energy ◽  
Power Output ◽  
Wave Energy Converter ◽  
Energy Converter

Numerical Simulation and Optimization of a Wave Energy Converter for the Izu Islands Sea in Japan

2014 ◽  
Author(s):  
Takeshi Kamio ◽  
Makoto Iida ◽  
Chuichi Arakawa
Keyword(s):  
Numerical Simulation ◽  
Wave Energy ◽  
Power Output ◽  
Test Site ◽  
Wave Energy Converter ◽  
Complex Conjugate ◽  
Maximum Output ◽  
Energy Converter ◽  
Simulation And Optimization ◽  
Izu Islands

The purpose of this study is the numerical simulation and control optimization of a wave energy converter to estimate the power at a test site in the Izu Islands. In Japan, ocean energy is once again being seriously considered; however, since there are many inherent problems due to severe conditions such as the strong swells and large waves, estimations are important when designing such devices. The numerical simulation method in this study combines the wave interaction analysis software WAMIT and an in-house time-domain simulation code using the Newmark-β method, and introduces approximate complex-conjugate control into the code. The optimized parameters were assessed for a regular sine wave and an irregular wave with a typical wave spectrum. With the optimized parameters, average and maximum output power were estimated for the observed wave data at the test site. The results show a more than 100 kW average power output and a several times larger maximum power output.

Evaluating Constant DC-Link Operation of Wave Energy Converter

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Rickard Ekström ◽  
Venugopalan Kurupath ◽  
Cecilia Boström ◽  
Rafael Waters ◽  
Mats Leijon
Keyword(s):  
Wave Energy ◽  
Power Output ◽  
Wave Energy Converter ◽  
Damping Factor ◽  
Energy Converter ◽  
Sea State ◽  
Voltage Level ◽  
Electromagnetic Damping ◽  
Point Of Common Coupling ◽  
Common Coupling

A wave energy converter (WEC) based on a linear generator and a point-absorbing buoy has been developed at Uppsala University. Interconnecting an array of WECs in parallel requires a point of common coupling, such as a common dc-bus. The dc voltage level seen by the generator is directly linked to the electromagnetic damping of the generator. A lower dc-level results in a higher damping factor and is important for increased absorption of the wave power. The drawback is increased losses in generator windings and cable resistance. There will be an optimal dc-level for maximum power output. This is a function of not only generator and buoy characteristics, but the current sea state. Experimental results of the full-scale system have been carried out, and used as validation of a simulation model of the system. The model is then used to evaluate how the dc-level seen by the generator influence the power output. The results indicate that higher dc-levels should be used at higher sea states, and power output may vary by up to a factor five depending on which dc-level is chosen.

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