• Journal of Wind Energy
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• v.14 no.4
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• pp.68-74
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• 2023

Research is being actively conducted to increase energy production by increasing the length of wind turbine blades. However, it is difficult to manufacture and transport large-scale blades. Various studies are being conducted on the concept of separate wind turbine blades considering transportation methods and maintenance. In this study, various methods of dividing blades and assembling the divided blades were reviewed. The position of the division when the blades are divided was analyzed.

• New & Renewable Energy
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• v.6 no.1
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• pp.12-19
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• 2010

In Korea, experiences in wind farm operation are limited and the foundation for setting standards in electrical system connection is still weak in comparison to the operation experience in connection of wind power to the electrical system of other countries around the world. Therefore, standards that are being applied in various countries for connection and optimal operation in wind farms need to be examined, and in addition, procedures for the assessment of the effects on the system are needed for setting connection standards and optimal operation plans in accordance with Korean electrical system characteristics. In this study, procedures for the assessment of effects of wind power connection to the electrical system are presented.

• Tribology and Lubricants
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• v.27 no.4
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• pp.204-208
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• 2011

Yaw brakes are used in wind turbines to control the orientation of blades to be perpendicular to the wind. These devices are very important machine elements because they are closely related to the overall efficiency of wind turbines. One unit of yaw brakes is composed of a friction pad and a caliper. In this study, a tangential force between the friction pad and the disk is calculated when the brake is acting in 750 kW wind turbine. Then, stress distribution and the deformation of the caliper are calculated using a finite element analysis. An experimental equipment is also developed to verify the exactness of calculated results. The analytical and experimental results are presented and discussed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.124-129
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• 2010

Wind load characteristics is investigated for vibration analysis of wind turbine gearbox. A normal wind model assumed, of which the wind velocity is increased according to the height from ground. A blast wind model is assumed, of which the maximum velocity is located at the center and the velocity profile is normally distributed. The periodical torque and bending moments transmitted to the main shaft of wind turbine are investigated. The average values and the harmonic terms of the transmitted moments are studied on the wind direction of range $-45^{\circ}{\sim}45^{\circ}$ and the bending moment characteristics are examined, which is regarded as the main source of the misalignment of gear train.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.11
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• pp.1571-1577
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• 2012

This paper presents a method for assessing the voltage sag performance of power system involving wind power generation. Wind power generation is considered as one of the most desirable renewable energy sources. However, wind power generation have uncertain energy output and it is difficult to control the output. The existing methods of voltage sag assessment are not reflected the characteristics of wind power generation. Therefore, in order to more accurately assess the voltage sag performance, the probability of wind power operation is evaluated. In this paper, the probability is determined by combining the wind speed model with the output curve of wind turbine. The probability of wind power operation is reflected as a parameter in voltage sag assessment. The proposed method can provide more accurate results of voltage sag assessment for the case involving the wind power generation.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.269-272
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• 2006

Numerical analysis of wind turbine scale effect was performed by using computational fluid dynamics. For the numerical analysis of wind turbine. Three dimensional Navier-Stokes solver with various turbulence models was tested and realizable k-e turbulence model was selected for the simulation of wind turbines. To validate the present method, performance of NREL (National Renewable Energy Laboratory) Phase VI wind turbine model was analyzed and compared with experiment and blind test data. Using the present method, numerical simulations for various size of wind tunnel model were carried out and characteristics were observed in detail. The power loss due to the interference between wind turbine and nacelle was also computed for relatively larger nacelle installation in wind tunnel test. The present results showed good correlations with experimental data and reasonable trends of scale effect of wind turbine.

• Journal of Environmental Science International
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• v.25 no.2
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• pp.247-257
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• 2016

To predict annual energy production (AEP) accurately in the wind farm where located in Seongsan, Jeju Island, Equivalent wind speed (EQ) which can consider vertical wind shear well than Hub height wind speed (HB) is calculated. AEP is produced by CFD model WindSim from National wind resource map. EQ shows a tendency to be underestimated about 2.7% (0.21 m/s) than HB. The difference becomes to be large at nighttime when wind shear is large. EQ can be also affected by atmospheric stability so that is classified by wind shear exponent (${\alpha}$). AEP is increased by 11% when atmosphere becomes to be stabilized (${\alpha}$ > 0.2) than it is convective (${\alpha}$ < 0.1). However, it is found that extreme wind shear (${\alpha}$ > 0.3) is hazardous for power generation. This results represent that AEP calculated by EQ can provide improved accuracy to short-term wind power forecast and wind resource assessment.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.81-84
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• 2008

This paper discussed the validity of wind force power generation in consideration of the topographical characteristics of Korea. In order to estimate the exact generation of wind power plants, we analyzed and compared wind resources in mountain areas and plain areas by introducing not only wind velocity, the most important variable, but also wind distribution and wind standard deviation that can reflect the influence of landform sufficiently. According to the results of this study, generation was higher at wind power plants installed in southwestern coastal areas where wind velocity was low than at those installed in mountain areas in Gangwondo where wind velocity was high. This suggests that the shape parameter of wind distribution is low due to the characteristics of mountain areas. and the standard deviation of wind velocity is large due to the effect of mountain winds, and therefore, actual generation is low in mountain areas although wind velocity is high.

• Wind and Structures
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• v.34 no.3
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• pp.291-301
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• 2022

Although mostly used in wind turbine market, single rotor wind turbines have problems with transportation and installation costs due to their large size. In order to solve such problems, multi-rotor wind turbine is being proposed; however, light weight design of multi-rotor wind turbine is required considering the installation at offshore or deep sea. This study proposes the systematic design process of the multi-rotor wind turbine focused on its supporting structure with simultaneous consideration of static and dynamic behaviors in an ideal situation. 2D and successive 3D topology optimization process based on the density method were applied to minimize the compliance of supporting structure. To realize the conceptual design obtained by topology optimization for manufacturing feasibility, the derived 3D structure was modified to have shell structures and optimized again through parametric design using the design of experiments and the response surface method for detail design of their thicknesses and radii. The resultant structure was determined to satisfy the stress and the buckling load constraint as well as to minimize the weight and the resultant supporting structure were verified numerically.

• The KSFM Journal of Fluid Machinery
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• v.15 no.4
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• pp.42-49
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• 2012

This study is performance estimation of wind augmentation device for BiWP(Building-integrated Wind Power) which recently attracts attention as a local power. various structures are installed on a rooftop of residential complex buildings. Changing a profile of these, we designed a configuration that is able to capture much air and increase exit velocity. To estimate wind augmented effect of this device, we compared numerical analysis results with wind tunnel test results. Results show that exit velocity is increased from 24% to 60% by wind augmented device on a rooftop of building.