• 한국신재생에너지학회:학술대회논문집
• /
• 2009.06a
• /
• pp.463-466
• /
• 2009

The numerical simulation optimized by Four Dimensional Data Assimilation (FDDA) with Quick Scatterometer (QuikSCAT) data is carried out to evaluate wind resource characteristics at various heights in the southeastern area of the Korean Peninsula, where wind farms are planned to be built on on- and off-shore as well as comparable diurnal wind variations are characterized at the surface. The temporal and spatial distributions of modeled wind speeds showed good agreement with the observations based on the temporal variation analysis. Model results indicate that the higher model is performed in resolution, the more precise results is at turbine hub height. Occasionally, wind speed variations for each numerical resolution has a different regional and seasonal variations. In the coast area, hub height wind speed of 9km-resolution is simillar to that of 3km-resolution. On the other hand, hub height wind speed of 3km-resolution is simillar to that of 1km-resolution in the Jiri mountainous area.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.49 no.12
• /
• pp.963-969
• /
• 2021

The wind data measured from local meteorological masts is used to evaluate wind speed distribution and energy production in the specified site for wind farm However, wind data measured from meteorological masts often contain missing information or insufficient desired height or data length, making it difficult to perform wind turbine control and performance simulation. Therefore, long-term continuous wind data is very important to assess the annual energy production and the capacity factor for wind turbines or wind farms. In addition, if seasonal influences are distinct, such as on the Korean Peninsula, wind data with seasonal characteristics should be considered. This study presents methodologies for generating synthetic wind that take into account fluctuations in both wind speed and direction using the hidden Markov model, which is a statistical method. The wind data for statistical processing are measured at Maldo island in the Kokunnsan-gundo, Jeonbuk Province using the Automatic Weather System (AWS) of the Korea Meteorological Administration. The synthetic wind generated using the hidden Markov model will be validated by comparing statistical variables, wind energy density, seasonal mean speed, and prevailing wind direction with measurement data.

• The KSFM Journal of Fluid Machinery
• /
• v.18 no.6
• /
• pp.63-70
• /
• 2015

This paper proposes a novel airfoil named "KA2" for the blade of the wind turbine systems. Dynamic loads characteristics are analyzed and compared using aerodynamic data of ten airfoils including the proposed airfoil. The blade is divided into the sixteen elements in the longitudinal direction of the blade for applying the Blade Element Method Theory (BEMT) method, and in each element, torque, thrust, and pitching moment are calculated using turbulent time varying wind speed and aerodynamic data of each wing. Additionally, each force and torque is accumulated in the whole region of the blade for the estimation of representative values. The magnitude of such forces is comparatively analyzed for different airfoils. The angle of attack is constant below the rated wind speed due to the fact that the tip speed ratio is kept at the constant value, and it increases in the region of over rated wind speed as the tip speed ratio decreasing with constant rated rpm and increasing wind speed. Such increase in the angle of attack causes the changes of the force acting on the airfoil with different characteristics of lift and drag in the stall region of each different airfoil. Even though the mean wind speed is in the rated speed in a given time, because of the turbulence, it has either the over rated or under rated speed most of the time. Furthermore, the dynamic properties of each force are analyzed in this rated wind speed in order to objectively understand the dynamic properties of the blades which are designed based on the different airfoils. These dynamic properties are also compared by the standard deviation of time varying characteristics. Moreover, the output characteristics of the wind turbine are investigated with different airfoils and wind speeds. Based on these investigations, it was revealed that the proposed airfoil (KA2) is well applicable to the blade with passive pitch control system.

• Journal of the Korean Solar Energy Society
• /
• v.31 no.3
• /
• pp.89-94
• /
• 2011

In this study, we measured the wind data as new and renewable energy resources and carried out the evaluation of uncertainty about these data with the authentic standards. These data collected at the 20 locations in korea. We carried out the processing and evaluation about these data with standards as ISO, GUM, and IEC. Whereby these data become standards data and the credibility are gained. These data include some information as direction, humidity, pressure, temperature, and energy density. The annual average of wind speed(in Hamo) was measured as 9.5m/s, then the uncertainty was evaluated as ${\pm}0.88m/s$. We judge the credibility of data by expression of reliability quantitatively. In additional, the standards data is able to approach anywhere and it will be used to support of related research and industry.

• Atmosphere
• /
• v.18 no.4
• /
• pp.493-506
• /
• 2008

In order to examine the variational features of Asian dust outbreak in recent years, observed WMO synop data were employed for the period from 1996 to 2007. We first divided Asian dust source regions into four subregions; 1) Taklamakan, 2) Gobi, 3) Inner Mongolia-Manchuria and 4) Loess, and the meteorogical variables such as wind speed, precipitation and threshold wind speed observed during the Asian dust outbreak period were compared with those during non-Asian dust period. The results showed that temporal variation of occurrence frequency of dust outbreak had a strong positive correlation with the frequency of strong wind speed and low precipitation in each of the 4 source regions. Spatial distributions of frequency of dust occurrence after 2002 showed increasing trend in Gobi and Inner Mongolia-Manchuria but decreasing trend in Loess region. This is showing a shift in main source region toward Northwest, especially since 2003.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.1068-1069
• /
• 2015

Wind turbines have an enormous potential for decentralized electricity generation. In recent years, there has been an increasing worldwide interest in small/medium wind systems. This paper presents the results of power performance testing conducted on a 50 kW turbine located in Yeonggwang test-bed. The turbine system is a pitch, active yaw, variable speed, upwind, three blade with a direct drive PMSG. This thesis covers the operation of variable speed wind turbines with pitch-yaw control. The system considered is controlled to generate maximum energy while minimizing loads. The data include power, wind speed, and direction from meteorological towers, and nacelle anemometer readings and output from turbine. The analysis concentrates on the effect of the load on the power-wind speed curve of the turbine.

• Wind and Structures
• /
• v.18 no.6
• /
• pp.619-631
• /
• 2014

This paper proposes new criteria to fix hidden neuron in Multilayer Perceptron Networks for wind speed prediction in renewable energy systems. To fix hidden neurons, 101 various criteria are examined based on the estimated mean squared error. The results show that proposed approach performs better in terms of testing mean squared errors. The convergence analysis is performed for the various proposed criteria. Mean squared error is used as an indicator for fixing neuron in hidden layer. The proposed criteria find solution to fix hidden neuron in neural networks. This approach is effective, accurate with minimal error than other approaches. The significance of increasing the number of hidden neurons in multilayer perceptron network is also analyzed using these criteria. To verify the effectiveness of the proposed method, simulations were conducted on real time wind data. Simulations infer that with minimum mean squared error the proposed approach can be used for wind speed prediction in renewable energy systems.

• Journal of the Korean Solar Energy Society
• /
• v.30 no.4
• /
• pp.9-14
• /
• 2010

The main cause of global warming is carbon dioxide generated from the use of fossil fuels, and active research on the reduction of carbon is in progress to slow down the increasing global warming. Wind turbines generate electricity from kinetic energy of wind and are considered as representative for an energy source that helps to reduce carbon emission. Since the kinetic energy of wind is proportional to the cube of the wind speed, the intensity of wind affects wind farm construction validity the most. Therefore, to organize a wind farm, validity analysis should be conducted first through measurement of the wind resources. To facilitate the approval and permission and reduce installation cost, measuring sensors should be installed at locations below the actual wind turbine hub. Wind conditions change in shape with air density, and air density is most affected by the variable sterrain and surface type. So the magnitude of wind speed depends on the ground altitude. If wind conditions are measured at a location below the wind turbine hub, the wind speed has to be extrapolated to the hub height. This correction of wind speed according to height is done with the Deacon equation used in the statistical analysis of previously observed data. In this study, the optimal Deacon equation parameter was obtained through the analysis of the correction of the wind speed error with the Deacon equation based on the characteristics of terrain.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.37 no.11
• /
• pp.1121-1130
• /
• 2009

In order to investigate the offshore wind resources, the measured data from the QuikSCAT satellite was analyzed from Jan 2000 to Dec 2008. QuikSCAT satellite is a specialized device for a microwave scatterometer that measures near-surface wind speed and direction under all weather and cloud conditions. Wind speed measured at 10 m above from the sea surface was extrapolated to the hub height by using the power law model. It has been found that the high wind energy prevailing in the south sea and the east sea of the Korean peninsula. From the limitation of seawater depth for piling the tower and archipelagic environment around the south sea, the west and the south-west sea are favorable to construct the large scale offshore wind farm, but it needs efficient blade considering relatively low wind speed. Wind map and monthly variation of wind speed and wind rose using wind energy density were investigated at the specified positions.

• Journal of Korean Society for Atmospheric Environment
• /
• v.14 no.6
• /
• pp.607-620
• /
• 1998

The influence of transportation on air quality has been elevating in urban area. Air pollutants from automobiles cause primary and secondary air pollution, and need to be tightly controlled. In this study, the effect of automobile air pollutants on highway vicinity area was evaluated by the comparison of field measurement. and target was for modeling using CALINE3, NO2 was the target for this work. It was found that the concentration predicted by CALINE3 is overestimated at low wind speed and input data of wind speed requires correction. Based on the measured data, the wind speed was modified by effective wind speed equation [Ue=U+0.24·EXP(-pxU)], and there after the accuracy of CALINE3 calculation was improved neighborhood area of highway. It was also observed that weather conditions and traffic volume affect the concentration of air pollution. Finally, the NO2 effect of automobile air pollutants on the vicinity area of highway proved to be up to 400∼600m from the highway.