
Atsushi YamaguchiAshikaga University
Atsushi Yamaguchi
Doctor of Philosophy
About
69
Publications
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517
Citations
Introduction
Skills and Expertise
Education
April 2000 - March 2002
April 1995 - March 2000
Publications
Publications (69)
This study proposes a microscale flow model to estimate mean wind speed, fluctuating wind speed and wind direction over complex terrain considering the effects of topography, atmospheric stability, and turbine wakes. Firstly, the effect of topography is considered using Computational Fluid Dynamics (CFD). Next, a mesoscale model is presented to acc...
In this study, the comparisons of the measured turbulence intensity by a Doppler lidar with the reference value in synthetic turbulent wind field are carried out. The standard deviation of the horizontal velocity components measured by the pulsed lidar shows larger value than the reference. Two correction methods are proposed to explain and improve...
For the design of floating offshore wind turbines (FOWT), all the load cases need to be calculated by using a coupled model of wind turbine and platform, while the uncoupled approach will help to reduce the number of simulations for the design and optimization of floating offshore wind turbines. In this study, the effects of the wind and wave actio...
A maximum instantaneous wind speed forecast methodology based on the autoregressive with exogenous inputs (ARX) model is proposed, in which numerical weather prediction and on-site measurement are used as inputs and the model parameters are estimated using non-parametric regression with forgetting factors. The accuracy of prediction using a propose...
An advanced pitch controller is proposed for the load mitigation of wind turbines. This study focuses on the nacelle acceleration feedback control and lidar-based feedforward control, and discusses how these controllers contribute to reduce the load on wind turbines. The nacelle acceleration feedback control increases the damping ratio of the first...
LiDAR-based wind speed measurements have seen a significant increase in interest in wind energy. However, reconstruction of wind speed vector from a LiDAR-measured radial wind speed is still a challenge. Furthermore, for extensive application of LiDAR technology, it can be used as a means to validate simulation and analytical models. To that end, t...
The floater motion and tower loading characteristics are investigated by using full scale measurement data obtained at Fukushima FOWARD project. Firstly, a method to measure the transverse component of floater motion is proposed by combining the integrated acceleration and missing GPS data in frequency domain. The proposed method improves measureme...
Wind turbines have to be designed against extreme load during power production with the recurrence period of 50 years. This extreme load is usually calculated through statistical extrapolation. However, large uncertainties exist in the estimation of the extreme load. This study aims to reduce these uncertainties in the statistical extrapolation by...
A gust forecasting based on ARX (Autoregressive with Exogenous inputs) model which uses numerical weather prediction and on-site measurement as inputs was proposed and the model parameters were estimated by using non-parametric regression with forgetting factors. The prediction accuracy by using dynamically adaptive model was improved compared to t...
Control logic can be defined as the software platform which provides the basis of applying control demands to the wind turbine. This platform consists of filters, mathematical operators, software computations, signal processing, controllers and all other interactive programs needed to govern the wind turbine. Noticeably, this control logic can affe...
The structural damping is an important parameter in the seismic resistant design of wind turbine. In this study, the effect of soil properties on modal damping is studied. Firstly, a sway-rocking model is built to simulate soil-structure interaction, and results show that sway-rocking model simulates second mode shape better than fixed-foundation m...
Metocean measurement at Fukushima test site was carried out and metocean characteristics were investigated. The effect of met mast tower on the measured wind speed can be mitigated by using the CFD simulation. Furthermore, the corrected wind speed data from the cup anemometer show good agreement with the wind speed measured by Lidar. The prevailing...
In this study, wave hindcasting was performed at Fukushima floating offshore wind turbine demonstration site by using Wave Watch III, and the simulation results were validated by using measurement data. Following results were obtained. It was found that the use of the computational domain which covers whole the Pacific Ocean improves the prediction...
This study evaluates scanning Doppler Lidar-based wind field measurement and analysis techniques for wind energy applications. The Lidar measurements are first validated against measurements from existing V1 Lidar. It is found that the availability of 20% (30 data per 10 minutes) is sufficient to produce fairly good 10 minutes averaged wind speed a...
A gust forecasting based on ARX model which uses numerical weather prediction and on-site measurement as inputs was proposed and the model parameters were estimated by using non-parametric regression with forgetting factors. The prediction accuracy of the dynamically adaptive model was improved compared to the conventional static MOS (Model Output...
Due to the restrictions of the structure design of the met mast on the floater, the effect of met mast on the wind speed measurement is not negligible. In this study, flow simulation around the met mast of Fukushima FORWarD is carried out to correct the effect of the met mast. Simulated wind speed ratio between two anemometers shows good agreement...
In this study, a new motion compensation algorithm was proposed and verified by using numerical simulation. Compensated horizontal mean wind speed by using conventional method shows good agreement with reference wind speed regardless of the motion of the floater. However, turbulence intensity is always overestimated. The overestimation is more sign...
Numerical predictions of sea currents are carried out for one year by using Princeton Ocean Model (POM) and validated by using measurement data at Fukushima Floating Offshore wind farm demonstration site. Predicted current speed and direction show good agreement with measurement. Then, a method for the prediction of the variation of annual average...
The extreme wind speed at an offshore location was predicted using Monte Carlo simulation (MCS) and measure-correlate-predict (MCP) method. The Gumbel distribution could successfully express the annual maximum wind speed of extratropical cyclone. On the other hand, the estimated extreme wind speed of tropical cyclones by analytical probability dist...
Offshore wind climate along the coast of Kanto area was investigated by a mesoscale model and wind energy potential considering economical and social criteria was estimated by Geographical Information System (GIS). The prediction accuracy of the annual mean wind speed by the mesoscale model was 2.49%. The estimated wind climate shows that offshore...
In this study, an ARX model with nonparametric multi time scale regression model was proposed for short term gust forecasting and applied to a ski resort in Japan. Proposed ARX model can be used for short term forecasting of mean and fluctuating wind speed. Proposed nonparametric multi time scale regression model can appropriately estimate the peak...
This study examines applicability of Normal Turbulence Model (NTM) in IEC61400-1 for offshore conditions using wind records obtained at an offshore site. The model parameters for estimation of the standard deviation of longitudinal fluctuating velocity, σ1, in NTM are presented. The identified model parameters for the mean value of σ1 agree well wi...
To reduce the cost of operation and maintenance of wind turbines, a physical model and simulation-based condition monitoring strategy is investigated. To obtain a reliable performance evaluation of the wind turbine using simulations, it is necessary to ensure that the simulated external force is accurate and close to the actual load. Hence, this st...
The extreme wind speed at an offshore location is predicted using Monte Carlo simulation (MCS) and Measure-Correlate-Predict (MCP) method. The Gumbel distribution can successfully express the annual maximum wind speed of extratropical cyclone. On the other hand, the analytical probability distribution underestimates annual maximum wind speed of tro...
This workaims to show the results of the planning and development of a single VAWT’s installation in a Northern Italy rural area featured by badlands. Satellite data, given by ASI (“Agenzia Spaziale Italiana” – COSMO-SkyMed SAR), allowed the mapping of roughness, through land cover and land use mapping.
In this study, an approach to combine the physical model and statistical model was proposed to reduce the initial error of the wind power forecasting. Using the result of the physical model as an initial value of the statistical model, the prediction accuracy was improved. Implementing the virtual training with the measured wind speed and the physi...
The applicability of Dynamical Statistical Downscaling Procedure to wind prediction along railway tracks was examined. By combining a mesoscale wind climate database with a non-linear flow simulation model, MASCOT, the prediction of the wind climate at any sites along the railway track in Japan was made possible. The predicted results showed better...
A wind generation method linked to time series of measured wind speed is expanded and applied to FEM for the response analysis of wind turbine support structures. Results indicate that the mean, the standard deviation and the maximum of the tower bending moments with both conventional wind generation method and proposed method demonstrate a good ag...
In this study, a generalize canopy model that can consider vegetation, buildings and porous obstacles is proposed. Flow field around two obstacles with different porosities are simulated. The results show a good agreement with the measurement. A wind tunnel test of the scale model of a city is also performed and simulated flow field by proposed mod...
A wind generation method linked to time series of measured wind speed is expanded and applied to FEM for the response analysis of wind turbine support structures. Results indicate that the mean, the standard deviation and the maximum of the tower bending moments with both conventional wind generation method and proposed method demonstrate a good ag...
This paper reports a wind power forecast model based on ARX model based on multi timescale model to accurately predict the wind power including the effect of operating condition. A wind power forecast model based on ARX model with multi timescale parameter was developed and the improvement of the prediction accuracy was verified by comparing the me...
In this study, wind prediction method for the train operation based on the onsite measurement and the numerical simulation. Figure 1 shows the flow of the method. First, from one year simulation by mesoscale model and microscale model, the wind speed ratio and the change in wind direction between the site of interest and the measurement site are ca...
In order to implement the numerical weather prediction with fine resolution to the on-line forecasting system, transfer coefficient method was proposed. Multi-timescale model (ARXM) was developed to account for the sudden change of the output from the wind farm due to the operational trouble. The performance of the proposed method was verified by t...
In this study, a typical upscaling approach was investigated systematically to clarify the effects of the number and location of reference wind farms on the expected power output of a whole region and its error. It was found that the prediction error for the power output of a whole region depends on the number of reference wind farms (RWFs). The pr...
Offshore wind climate along the coast of Kanto area was investigated by a mesoscale model and wind energy potential considering economical and social criteria was estimated by Geographical Information System (GIS). The prediction accuracy of the annual mean wind speed by the mesoscale model was 4.8%. The estimated wind climate shows that offshore C...
A Dynamical Statistical Downscaling Procedure (DSDP) was proposed and verified at Tappi Cape, north of Japan. This method first dynamically predicts the regional wind by mesoscale atmospheric model with horizontal resolution of 1km. Next, regional wind is statistically analyzed to determine regional wind climate. Then, regional wind climate is down...
Development of the offshore wind energy would be a key strategy to increase wind penetration in Japan. In this study, the offshore wind energy potential around the offing of Iwaki, in the Pacific Ocean, was investigated using mesoscale meteorological model and compared with the measurement. A mesoscale model RAMS with the horizontal resolution of 2...
In this study mesoscale meteorological model and CFD model was used to downscale the nu-merical weather prediction (NWP) data and verified at Hachijo Jima wind power plant. To reduce the compu-tational cost of mesoscale model, coefficient matrix method was proposed. Following results were obtained. The root mean square error (RMSE) was reduced to 3...
Computational domain size required for the numerical prediction of flow over a two-dimensional ridge and a three-dimensional hill was investigated by changing the computational domain heights and widths and the distances between the terrain and the inlet boundary. It was found that the compu-tational domain heights should be decided so that the blo...
In this study mesoscale meteorological model and CFD model was used to downscale the numerical weather prediction (NWP) data and verified at Hachijo Jima wind power plant. To reduce the computational cost of mesoscale model, coefficient matrix method was proposed. Following results were obtained. The root mean square error (RMSE) was reduced to 3.1...
Offshore wind energy potential in the supply area of Tokyo Electric Power Company (TEPCO) was investigated by using mesoscale model and geographical information system (GIS). Following results were obtained. 1) Wind climate predicted by mesoscale model shows good agreement with the observation and the prediction error of annual mean wind speed was...
This paper reports damages of wind turbines on Miyakojima Island by Typhoon Maemi on September 11, 2003. Maemi struck the island with an average wind speed of 38.4 m/s and a maximum gust of 74.1 m/s, recorded at Miyakojima meteorological station. All six wind turbines operated by Okinawa Electric Power Company were extensively damaged. Two Micon M7...
Maximum wind speed at Miyakojima Island during typhoon 0314 was investigated by means of wind tunnel test and numerical simulation. Following results were obtained. 1) Wind speed measured at Miyakojima Meteorological Station was affected by surrounding buildings, causing remarkable decrease of wind speed. 2) Wind speed over flat terrain was estimat...
This paper reports damages of wind turbines on Miyakojima Island by Typhoon Maemi on September 11, 2003. Maemi struck the island with an average wind speed of 38.4m/s and a wind gust of 74.1m/s, recorded at Miyakojima meteorological station. All six wind turbines operated by Okinawa Electric Power Company were extensively damaged. Two Micon M750/40...
Offshore wind energy potential in the supply area of Tokyo Electric Power Company (TEPCO) was investigated by using mesoscale model and geographical information system (GIS) assuming some scenarios considering social and economical criteria. Following results were obtained. Predicted wind climate by mesoscale model shows good agreement with measure...
Required computational domain size was investigated and new boundary treatments and numerical solution method were proposed for the numerical prediction of local wind in complex terrain and were verified by a wind tunnel test. The effect of computational domain height, width and the position of the inlet boundary on the flow field was examined. Buf...
Wind flow over complex and steep terrain was investigated by a wind tunnel experiment and a numerical simulation. The mean value and the turbulence of the wind flow over complex terrain in a coastal region of Japan were measured by split-fiber and X-wire probes. It was found that the split-fiber probe can give a reasonable accuracy while the conven...
A Dynamical Statistical Downscaling Procedure was proposed and verified at Tappi Cape, north of Japan. This method first dynamically predicts the regional wind by mesoscale atmospheric model with horizontal resolution of 1km. Next, regional wind is statistically analyzed to determine regional wind climate. Then, regional wind climate is downscaled...
The applicability of the conventional linear model and the developed nonlinear model to the flow in steep and complex terrain were investigated. For flows over two-dimensional ridges, the linear model considerably overestimates the wind speed when the slope angle exceeds 20 degree due to the inability of predicting flow separation. For the flow ove...