• Title, Summary, Keyword: Wind speed

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Prediction of Wind Damage Risk based on Estimation of Probability Distribution of Daily Maximum Wind Speed (일 최대풍속의 추정확률분포에 의한 농작물 강풍 피해 위험도 판정 방법)

  • Kim, Soo-ock
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.19 no.3
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    • pp.130-139
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    • 2017
  • The crop damage caused by strong wind was predicted using the wind speed data available from Korean Meteorological Administration (KMA). Wind speed data measured at 19 automatic weather stations in 2012 were compared with wind data available from the KMA's digital forecast. Linear regression equations were derived using the maximum value of wind speed measurements for the three-hour period prior to a given hour and the digital forecasts at the three-hour interval. Estimates of daily maximum wind speed were obtained from the regression equation finding the greatest value among the maximum wind speed at the three-hour interval. The estimation error for the daily maximum wind speed was expressed using normal distribution and Weibull distribution probability density function. The daily maximum wind speed was compared with the critical wind speed that could cause crop damage to determine the level of stages for wind damage, e.g., "watch" or "warning." Spatial interpolation of the regression coefficient for the maximum wind speed, the standard deviation of the estimation error at the automated weather stations, the parameters of Weibull distribution was performed. These interpolated values at the four synoptic weather stations including Suncheon, Namwon, Imsil, and Jangsu were used to estimate the daily maximum wind speed in 2012. The wind damage risk was determined using the critical wind speed of 10m/s under the assumption that the fruit of a pear variety Mansamgil would begin to drop at 10 m/s. The results indicated that the Weibull distribution was more effective than the normal distribution for the estimation error probability distribution for assessing wind damage risk.

Performance Comparison of Two Wind Turbine Generator Systems Having Two Types of Control Methods

  • Saito, Sumio;Sekizuka, Satoshi
    • International Journal of Fluid Machinery and Systems
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    • v.2 no.1
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    • pp.92-101
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    • 2009
  • The purpose of this paper is to gain a greater understanding of the performance of practical wind turbine generating systems with differing output power controllers and controlling means for wind turbine speed. Subjected wind turbines, both equipped with an asynchronous power generator, are located at two sites and are defined as wind turbine A and wind turbine B in this study, respectively. Their performance differences are examined by measuring wind speed and electric parameters. The study suggests that both wind turbines have a clear linkage between current and output power fluctuations. Comparison of the fluctuations to wind speed fluctuation, although they are triggered primarily by wind speed fluctuation, clearly indicates the specific behaviors inherent to the respective turbine control mechanisms.

Analysis of aerodynamic characteristics of 2 MW horizontal axis large wind turbine

  • Ilhan, Akin;Bilgili, Mehmet;Sahin, Besir
    • Wind and Structures
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    • v.27 no.3
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    • pp.187-197
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    • 2018
  • In this study, aerodynamic characteristics of a horizontal axis wind turbine (HAWT) were evaluated and discussed in terms of measured data in existing onshore wind farm. Five wind turbines (T1, T2, T3, T4 and T5) were selected, and hub-height wind speed, $U_D$, wind turbine power output, P and turbine rotational speed, ${\Omega}$ data measured from these turbines were used for evaluation. In order to obtain characteristics of axial flow induction factor, a, power coefficient, $C_p$, thrust force coefficient, $C_T$, thrust force, T and tangential flow induction factor, a', Blade Element Momentum (BEM) theory was used. According to the results obtained, during a year, probability density of turbines at a rotational speed of 16.1 rpm was determined as approximately 45%. Optimum tip speed ratio was calculated to be 7.12 for most efficient wind turbine. Maximum $C_p$ was found to be 30% corresponding to this tip speed ratio.

Detecting artefacts in analyses of extreme wind speeds

  • Cook, Nicholas J.
    • Wind and Structures
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    • v.19 no.3
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    • pp.271-294
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    • 2014
  • The impact of artefacts in archived wind observations on the design wind speed obtained by extreme value analysis is demonstrated using case studies. A signpost protocol for detecting candidate artefacts is described and its performance assessed by comparing results against previously validated data. The protocol targets artefacts by exploiting the serial correlation between observations. Additional "sieve" algorithms are proposed to identify types of correctable artefact from their "signature" in the data. In extreme value analysis, artefacts displace valid observations only when they are larger, hence always increase the design wind speed. Care must be taken not identify large valid values as artefacts, since their removal will tend to underestimate the design wind speed.

Proposal of Return Period and Basic Wind Speed Map to Estimate Wind Loads for Strength Design in Korea (강도설계용 풍하중 평가를 위한 재현기간과 기본풍속지도의 제안)

  • Ha, Young-Cheol
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.34 no.2
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    • pp.29-40
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    • 2018
  • Strength design wind loads for the wind resistance design of structures shall be evaluated by the product of wind loads calculated based on the basic wind speed with 100 years return period and the wind load factor 1.3 specified in the provisions of load combinations in Korean Building Code (KBC) 2016. It may be sure that the wind load factor 1.3 in KBC(2016) had not been determined by probabilistic method or empirical method using meteorological wind speed data in Korea. In this paper, wind load factors were evaluated by probabilistic method and empirical method. The annual maximum 10 minutes mean wind speed data at 69 meteorological stations during past 40 years from 1973 to 2012 were selected for this evaluation. From the comparison of the results of those two method, it can be found that the mean values of wind load factors calculated both probability based method and empirical based method were similar at all meteorological stations. When target level of reliability index is set up 2.5, the mean value of wind load factors for all regions should be presented about 1.35. When target level of reliability index is set up 3.0, wind load factor should be presented about 1.46. By using the relationship between importance factor(conversion factor for return period) and wind load factor, the return periods for strength design were estimated and expected wind speeds of all regions accounting for strength design were proposed. It can be found that return period to estimate wind loads for strength design should be 500 years and 800 years in according to target level of reliability index 2.5 and 3.0, respectively. The 500 years basic wind speed map for strength design was suggested and it can be used with a wind load factor 1.0.

Fuzzy Modeling and Robust Stability Analysis of Wind Farm based on Prediction Model for Wind Speed (풍속 예측모델 기반 풍력발전단지의 퍼지 모델링 및 강인 안정도 해석)

  • Lee, Deogyong;Sung, Hwa Chang;Joo, Young Hoon
    • 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.

Power Control of Three Phase PWM Converter for Small-scale Wind Power using Flux Weakening Control in Over Wind Speed Region (과풍속 영역에서의 약계자 제어를 이용한 풍력발전용 3상 PWM 컨버터의 출력제어)

  • Ku, Hyun-Keun;Kim, Jae-Heung;Lee, Hyung-Uk;Kim, Jang-Mok
    • The Transactions of the Korean Institute of Power Electronics
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    • v.19 no.2
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    • pp.149-156
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    • 2014
  • This paper proposes the battery charging algorithm for small-scale wind power generator using three phase PWM converter. it is impossible to control output power of the converter in over wind speed region since back EMF of PMSG is higer than battery voltage. Therefore, battery charging algorithm is proposed to expand battery charging over wind speed region. The suggested method is using the q-axis current for battery charging in the rated wind speed region. In the over wind speed region after it lower back EMF of PMSG using d-axis current it can control output power of the converter. The validity of the proposed algorithm are verified by experiments.

Meteorological basis for wind loads calculation in Croatia

  • Bajic, Alica;Peros, Bernardin
    • Wind and Structures
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    • v.8 no.6
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    • pp.389-406
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    • 2005
  • The results of reference wind speed calculation in Croatia as a base for the revision of the Croatian standards for wind loads upon structures are presented. Wind speed averaged over 10 minutes, at 10 m height, in a flat, open terrain, with a 50-year mean return period is given for 27 meteorological stations in Croatia. It is shown that the greatest part of Croatia is covered with expected reference wind speeds up to 25 m/s. Exceptions are stations with specific anemometer location open to the bura wind which is accelerated due to the channelling effects of local orography and the nearby mountain passes where the expected reference wind speed ranges between 38 m/s and 55 m/s. The methodology for unifying all available information from wind measurements regardless of the averaging period is discussed by analysing wind speed variability at the meteorological station in Hvar.

Wind Estimation Power Control using Wind Turbine Power and Rotor speed (풍력터빈의 출력과 회전속도를 이용한 풍속예측 출력제어)

  • Ko, Seung-Youn;Kim, Ho-Chan;Huh, Jong-Chul;Kang, Min-Jae
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.4
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    • pp.92-99
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    • 2016
  • A wind turbine is controlled for the purpose of obtaining the maximum power below its rated wind speed. Among the methods of obtaining the maximum power, TSR (Tip Speed Ratio) optimal control and P&O (Perturbation and Observation) control are widely used. The P&O control algorithm using the turbine power and rotational speed is simple, but its slow response is a weak point. Whereas TSR control's response is fast, it requires the precise wind speed. A method of measuring or estimating the wind speed is used to obtain a precise value. However, estimation methods are mostly used, because it is difficult to avoid the blade interference when measuring the wind speed near the blades. Neural networks and various numerical methods have been applied for estimating the wind speed, because it involves an inverse problem. However, estimating the wind speed is still a difficult problem, even with these methods. In this paper, a new method is introduced to estimate the wind speed in the wind-power graph by using the turbine power and rotational speed. Matlab/Simulink is used to confirm that the proposed method can estimate the wind speed properly to obtain the maximum power.

Assessment of Wind Resource Around the Korean Peninsula by Using Marine Buoys Datasets (해상부이 데이터 분석을 통한 한반도 해역의 바람자원 평가)

  • Oh, Ki-Yong;Kim, Ji-Young;Lee, Jun-Shin
    • New & Renewable Energy
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    • v.7 no.1
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    • pp.15-21
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    • 2011
  • In recent years, many countries have been endeavoring to exploit the offshore wind energy in terms of overcoming the limitations of on-land wind energy. Considering that mountains cover 70 percent of the Korean Peninsula and arable plains for wind energy are negligibly small, Korean government aggressively drives the offshore wind development of the Korean Peninsula. As part of preliminary investigation of offshore wind resources, KEPCO-RI (Korea Electric Power Corporation-Research Institute) has been analyzing marine buoy datasets measured at 5 positions over the period of 12 years, including estimation of extreme wind speed. It can be observed that variation of yearly wind speed, monthly wind speed as well as frequency distribution of wind direction. Wind classes of buoy sites are estimated by extrapolated average wind speed using log law. In addition, wind turbine class based on IEC code is assessed for evaluation of suitable wind turbine.