Numerical Analysis on Hydraulic Power Take-Off for Wave Energy Converter and Power Smoothing Methods

2018 ◽  
Author(s):  
Yi-Hsiang Yu ◽  
Nathan Tom ◽  
Dale Jenne
Keyword(s):  
Wave Energy ◽  
Power Output ◽  
Control Method ◽  
Average Power ◽  
Wave Energy Converter ◽  
Energy Converter ◽  
Power Fluctuation ◽  
Electrical Grid ◽  
Smoothing Methods ◽  
Power Smoothing

One of the primary challenges for wave energy converter (WEC) systems is the fluctuating nature of wave resources, which require the WEC components to be designed to handle loads (i.e., torques, forces, and powers) that are many times greater than the average load. This approach requires a much greater power take-off (PTO) capacity than the average power output and indicates a higher cost for the PTO. Moreover, additional design requirements, such as battery storage, are needed, particularly for practical electrical grid connection, and can be a problem for sensitive equipment (e.g., radar, computing devices, and sensors). Therefore, it is essential to investigate potential methodologies to reduce the overall power fluctuation while trying to optimize the power output from WECs. In this study, a detailed hydraulic PTO model was developed and coupled with a time-domain hydrodynamics model (WEC-Sim) to evaluate the PTO efficiency for WECs and the trade-off between power output and fluctuation using different power smoothing methods, including energy storage, pressure relief mechanism, and a power-based setpoint control method. The study also revealed that the maximum power fluctuation for WECs can be significantly reduced by one order of magnitude when these power smoothing methods are applied.

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.

scholarly journals Using Flexible Blades to Improve the Performance of Novel Small-Scale Counter-Rotating Self-Adaptable Wave Energy Converter for Unmanned Marine Equipment

2019 ◽  
Vol 7 (7) ◽  
pp. 223 ◽  
Author(s):  
Sun ◽  
Shang ◽  
Luo ◽  
Lu ◽  
Wu ◽  
...  
Keyword(s):  
Output Power ◽  
Wave Energy ◽  
Power Supply ◽  
Simulation Analysis ◽  
Average Power ◽  
Wave Energy Converter ◽  
Small Scale ◽  
Energy Converter ◽  
Experimental Conditions ◽  
Blade Thickness

Unmanned marine equipment has been increasingly developed for open seas. The lack of efficient and reliable power supply is currently one of the bottlenecks restricting the practical application of these devices. In order to provide a viable power supply method for unmanned marine equipment, such as sonic buoys and sea robots, we originally propose a novel small-scale flexible blade wave energy converter (WEC) based on self-adaptable counter-rotating operation mechanism. The flexible blade WEC is designed on the basis of the rigid blade WEC with the caging device. This paper identifies the key factors affecting WEC performance through theoretical analysis. According to the numerical simulation analysis, the output mechanical power of the double-layer absorber is 12.8 W, and the hydraulic efficiency is 36.3%. The results of the verification experiment show that the peak power of WEC is 5.8 W and the average power is 3.2 W. The WEC with 65Mn flexible blade under most experimental conditions has the best performance when the blade thickness is 0.10 mm. The study shows that the new generation WEC can effectively overcome the excessive fluctuation of the output power of the previous generation WEC. The output power curve of the novel WEC is relatively smooth, which is conducive to its smooth operation and subsequent utilization and storage of electrical energy.

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.

scholarly journals A novel control method to maximize the energy-harvesting capability of an adjustable slope angle wave energy converter

2016 ◽  
Vol 97 ◽  
pp. 518-531 ◽  
Author(s):  
Nguyen Minh Tri ◽  
Dinh Quang Truong ◽  
Do Hoang Thinh ◽  
Phan Cong Binh ◽  
Dang Tri Dung ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Wave Energy ◽  
Control Method ◽  
Slope Angle ◽  
Wave Energy Converter ◽  
Energy Converter
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