• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.11
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• pp.753-759
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• 2004

This paper presents a modeling and simulation of a fuzzy controller for maximum power extraction of a grid-connected wind energy conversion system with a link of a rectifier and an inverter. It discusses the maximum power control algorithm for a wind turbine and proposes, in a graphical form, the relationships of wind turbine output, rotor speed, power coefficient, tip-speed ratio with wind speed when the wind turbine is operated under the maximum power control. The control objective is to always extract maximum power from wind and transfer the power to the utility by controlling both the pitch angle of the wind turbine blades and the inverter firing angle. Pitch control method is mechanically complicated, but the control performance is better than that of the stall regulation method. The simulation results performed on MATLAB will show the variation of generator's rotor angle and rotor speed, pitch angle, and generator output.

• Wind and Structures
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• v.9 no.1
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• pp.37-58
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• 2006

The paper describes a study about effects of upstream hills on design wind loads using two mathematical approaches: Computational Fluid Dynamics (CFD) and Artificial Neural Network (NN for short). For this purpose CFD and NN tools have been developed using an object-oriented approach and C++ programming language. The CFD tool consists of solving the Reynolds time-averaged Navier-Stokes equations and $k-{\varepsilon}$ turbulence model using body-fitted nearly-orthogonal coordinate system. Subsequently, design wind load parameters such as speed-up ratio values have been generated for a wide spectrum of two-dimensional hill geometries that includes isolated and multiple steep and shallow hills. Ground roughness effect has also been considered. Such CFD solutions, however, normally require among other things ample computational time, background knowledge and high-capacity hardware. To assist the enduser, an easier, faster and more inexpensive NN model trained with the CFD-generated data is proposed in this paper. Prior to using the CFD data for training purposes, extensive validation work has been carried out by comparing with boundary layer wind tunnel (BLWT) data. The CFD trained NN (CFD-NN) has produced speed-up ratio values for cases such as multiple hills that are not covered by wind design standards such as the Commentaries of the National Building Code of Canada (1995). The CFD-NN results compare well with BLWT data available in literature and the proposed approach requires fewer resources compared to running BLWT experiments.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.1
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• pp.22-28
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• 2014

This paper proposes the fuzzy modeling and robust stability analysis of wind farm based on prediction model for wind speed. Owing to the sensitivity of wind speed, it is necessary to study the dynamic equation of the variable speed wind turbine. In this paper, based on the least-square method, the wind speed prediction model which is varied by the surrounding environment is proposed so that it is possible to evaluate the practicability of our model. And, we propose the composition of intelligent wind farm and use the fuzzy model which is suitable for the design of fuzzy controller. Finally, simulation results for wind farm which is modeled mathematically are demonstrated to visualize the feasibility of the proposed method.

• Journal of Navigation and Port Research
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• v.29 no.7
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• pp.641-646
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• 2005

In cargo-working, it unavoidably happens that the quay crane slip along the rail and the container move from side to side. Especially, they involve a lot of risk in bad weather. The rail clamp is a mooring device to prevent that the quay crane slips along the rail due to bad weather or the wind blast while the quay crane do the cargo-working And it will play a greater role in port container terminal integration and automation To design the wedge type rail clamp, it is very important to determine the wedge angle. In this study, we expect that the design wind speed of the quay crane will change over 16m/s. Assuming that the design wind speed is 40m/s, we determined the proper wedge angle of the wedge type rail clamp for the 50ton class quay crane.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.2
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• pp.243-250
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• 2010

As the wind has become one of the fastest growing renewable energy sources, the key issue of wind energy conversion systems is how to efficiently operate the wind turbines in a wide range of wind speeds. Compared to fixed speed turbines, variable speed wind turbines feature higher energy yields, lower component stress and fewer grid connection power peaks. Generally, measurement of wind speed is required for the control of variable speed wind turbine system. However, wind speed measured by anemometers is not accurate owing to various reasons. In this work, a new control algorithm for variable speed wind turbine system based on Kalman filter which can be used for the estimation of wind speed and artificial neural network which can generate optimum rotor speed is proposed. Also, to verify the feasibility of the proposed scheme, various simulation studies are carried out by using Simulink in Matlab.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.6
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• pp.1007-1019
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• 2015

The determination of the required seawall height is usually based on the combination of wind speed (or wave height) and still water level according to a specified return period, e.g., 50-year return period wind speed and 50-year return period still water level. In reality, the two variables are be partially correlated. This may be lead to over-design (costs) of seawall structures. The above-mentioned return period for the design of a seawall depends on economy, society and natural environment in the region. This means a specified risk level of overtopping or damage of a seawall structure is usually allowed. The aim of this paper is to present a conditional risk probability-based seawall height design method which incorporates the correlation of the two variables. For purposes of demonstration, the wind speeds and water levels collected from Jiangsu of China are analyzed. The results show this method can improve seawall height design accuracy.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.401-407
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• 2004

This study proposes a interim development result for the l-㎾ class small wind turbine system, which is applicable to relatively low wind speed regions like Korea and has the variable pitch control mechanism. In the aerodynamic design of the wind turbine blade, parametric studies were carried out to determine an optimum aerodynamic configuration which is not only more efficient at low wind speed but whose diameter is not much larger than similar class other blades. A light composite structure, which can endure effectively various loads, was newly designed. In order to evaluate the structural design of the composite blade, the structural analysis was performed by the finite element method. Moreover both structural safety and stability were verified through the full-scale structural test.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.2
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• pp.161-170
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• 2002

A wind tunnel experiment was performed with the design wind speed of 50m/s to investigate the wind forces of Ieodo Ocean Research Station. The structure portion above water surface was modelled with 1/80 scale ratio. The wind force coefficients were determined from the force signals and compared to the results of a numerical study which was separately undertaken. Those results generally agreed well, and it is assured that the experimental data can be effectively used in the wind resistant design of the structure. Making use of the experimental force and pressure coefficients, the wind farce and moments acting on the overall upper structure of prototype are determined together with the wind pressures on local impervious facilities (main deck, solar panel and helideck).

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.4
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• pp.211-216
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• 2005

In this paper a robust controller using adaptive backstepping technique is proposed to control the speed of wind power generation system. To make wind power generation truly cost effective and reliable, advanced and robust control algorithms are derived to on-line adjust the excitation winding voltage of the generator based on both mechanical and electrical dynamics. This method is shown to be able to achieve smooth and asymptotic rotor speed tracking, as justified by analysis and computer simulation.

• Wind and Structures
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• v.23 no.6
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• pp.577-594
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• 2016

In this paper a practical modelling methodology is presented for a series of aero- servo- elastic- coupled numerical analyses of small wind turbine operation, with particular emphasis on variable speed generator modelling in various wind speed conditions. The following characteristics are determined using the available computer tools: the tip speed ratio as a function of the generator constant (under the assumption of constant wind speed), the turbine coefficient of power as a function of the tip speed ratio (the torque curve is modified accordingly and generator speed and power curves are plotted), turbine power curves and coefficient of power curve as functions of the incoming wind speed. The last stage is to determine forces and torques acting on rotor blades and turbine tower for specific incoming wind speeds in order to examine the impact of the stall phenomena on these values (beyond the rated power of the turbine). It is shown that the obtained results demonstrate a valuable guideline for small wind turbines design process.