Takeshi Kamio

Optimal Control Parameter Determination for an Oscillating Body Type Wave Energy Converter for Japan

The purpose of this study is to determine the optimal parameters for a control strategy of an oscillating body type wave energy converter (WEC) for a WEC development and demonstration project in Japan. We plan to use a reactive control strategy for calm sea states, because wave heights in the seas near around Japan is about 1 m in summer. We also developed a combined and tuned control strategy with both reactive and resistive controls, in which the control parameters are changed to sea states. The proposed control system achieves both better performance and safer operation. In this numerical study, we determine the control parameters for the sea states by the time-domain simulation using the Newmark–β method.Copyright

Experimental Analysis of the Wind Farm and Numerical Site Calibration

This paper mentions the difference of estimation methods for the Weibull distribution using the wind data that were measured at more than 300 locations to clarify the wind characteristics in a complex terrain. As the result, the Weibull distribution function is approximated the experimental wind data by the non-linear fitting method rather than the linear fitting method. Then the numerical site calibration with MASCOT which is the non-linear numerical wind prediction model and WaSP are run out on a complex terrain in Japan.Copyright

Analysis on Turbulent Flows using Large-eddy Simulation on the Seaside Complex Terrain

The purpose of this study is the Large-eddy Simulation (LES) of the turbulent wind on the complex terrain, and the first results of the simulation are described. The authors tried to apply the LES code, which was developed as an atmospheric simulator in Japan Agency for the Marine-Earth Science and Technology (JAMSTEC), to the wind prediction for the wind energy. On the wind simulation, the highest problem would be the boundary conditions, and the case in this paper was simplified one. The case study in this paper is the west wind on a complex terrain site, which is the wind from sea for the site. The steady flow was employed for the inlet condition, because the wind on the sea is the low turbulent wind, and almost all the turbulence would be generated by the roughness of the ground surface. The wall function was employed as the surface condition on the ground surface. The computational domain size was about 8 × 3 × 2.5 km3, and the minimum cell size was about 10 × 10 × 3 m3. The computational results, the vertical profile of the averaged wind speed and the turbulence intensity, agreed with the measurement by the meteorological masts. Moreover, the authors tried the analysis of the turbulence characteristics. The power spectrum density model, and the cross spectrum analyses gave the knowledge of the turbulent characteristics on the complex terrain and the hints for the domain and grid of the numerical analysis.

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

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.Copyright