• Wind and Structures
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• 제29권4호
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• pp.247-270
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• 2019

Wind-resistant design of existing cooling tower structures overlooks the impacts of rainfall. However, rainstorm will influence aerodynamic force on the tower surface directly. Under this circumstance, the structural response of the super-large cooling tower (SLCT) will become more complicated, and then the stability and safety of SLCT will receive significant impact. In this paper, surrounding wind fields of the world highest (210 m) cooling tower in Northwest China underthree typical wind velocities were simulated based on the wind-rain two-way coupling algorithm. Next, wind-rain coupling synchronous iteration calculations were conducted under 9 different wind speed-rainfall intensity combinations by adding the discrete phase model (DPM). On this basis, the influencing laws of different wind speed-rainfall intensity combinations on wind-driving rain, adhesive force of rain drops and rain pressure coefficients were discussed. The acting mechanisms of speed line, turbulence energy strength as well as running speed and trajectory of rain drops on structural surface in the wind-rain coupling field were disclosed. Moreover, the fitting formula of wind-rain coupling equivalent pressure coefficient of the cooling tower was proposed. A systematic contrast analysis on its 3D distribution pattern was carried out. Finally, coupling model of SLCT under different working conditions was constructed by combining the finite element method. Structural response, buckling stability and local stability of SLCT under different wind velocities and wind speed-rainfall intensity combinations were compared and analyzed. Major research conclusions can provide references to determine loads of similar SLCT accurately under extremely complicated working conditions.

• 한국지능시스템학회논문지
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• 제20권5호
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• pp.710-715
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• 2010

최근 풍력발전 시스템은 가장 빨리 발전하고 있는 신재생 에너지원중 하나로 각광을 받고 있으며, 풍력발전 시스템의 주된 관심사는 어떻게 광범위한 풍속의 변화에서도 효율적으로 시스템을 동작시키는 가에 있다. 일반적으로 풍속은 풍력발전시스템의 동특성에 큰 영향을 미치는 요소이다. 따라서 많은 풍력발전 제어 알고리듬은 성능향상을 위해 풍속의 측정을 요구하게 된다. 그러나 불행히도 풍속계와 같은 센서에 의한 실효 풍속의 정확한 측정은 어려운 실정이며 따라서 제어 시스템의 동작을 위해 풍속은 여러 가지 기법을 통해 추정되고 있는 실정이다. 이에 본 연구에서는 칼만 필터 및 신경망에 기반한 새로운 형태의 풍속 추정 기법을 제안하고 제안된 기법의 유용성 확인을 위해 다양한 형태의 시뮬레이션을 수행하고자 한다.

• Wind and Structures
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• 제37권2호
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• pp.117-131
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• 2023

Korea Design Standard (KDS) will be updated with two major revisions on the assessment of wind load and performance-based wind design (PBWD). Major changes on the wind load assessment are the wind load factor and basic wind speed. Wind load factor in KDS is reduced from 1.3 to 1, and mean recurrence interval (MRI) for basic wind speed increases from 100 years to 500 years considering the reduction of wind load factor. Additional modification is made including pressure coefficient, torsional moment coefficient and spectrum, and aeroelastic instability. Combined effect of the updates of KDS code on the assessment of wind load is discussed with the case study on the specified sites and building. PBWD is newly added in KDS code to consider the cases with various target performance, vortex-induced vibration, aeroelastic instability, or inelastic behavior. Proposed methods and target performance for PBWD in KDS code are introduced.

• 한국환경과학회지
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• 제25권2호
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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.

• 한국전자통신학회논문지
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• 제10권8호
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• pp.935-944
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• 2015

본 논문에서는 가변속 풍력발전시스템의 동적 모델링과 운전제어 시뮬레이션을 수행하였다. 풍속모델, 풍력터빈과 PMSG 모델, MPPT 및 피치 운전제어 모델 등을 구현하였다. 그리고 상용화된 5MW급 풍력터빈 데이터들을 참고하여 실제적인 시스템과 유사한 출력계수 및 가상 운전 조건으로 시뮬레이션 하였다. 시뮬레이션 결과 정격속도 12[m/s]까지 최대출력계수를 유지하면서 최대전력추종을 확인하였다. 또한 12[m/s]이상의 고속 풍속에서는 동적으로 피치 각도를 제어하면서, 정격상태의 안정적인 출력을 유지하였다.

• 전력전자학회논문지
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• 제19권2호
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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.

• Smart Structures and Systems
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• 제24권6호
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• pp.733-744
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• 2019

Wind speed forecasting is critical for a variety of engineering tasks, such as wind energy harvesting, scheduling of a wind power system, and dynamic control of structures (e.g., wind turbine, bridge, and building). Wind speed, which has characteristics of random, nonlinear and uncertainty, is difficult to forecast. Nowadays, machine learning approaches (generalized regression neural network (GRNN), back propagation neural network (BPNN), and extreme learning machine (ELM)) are widely used for wind speed forecasting. In this study, two schemes are proposed to improve the forecasting performance of machine learning approaches. One is that optimization algorithms, i.e., cross validation (CV), genetic algorithm (GA), and particle swarm optimization (PSO), are used to automatically find the optimal model parameters. The other is that the combination of different machine learning methods is proposed by finite mixture (FM) method. Specifically, CV-GRNN, GA-BPNN, PSO-ELM belong to optimization algorithm-assisted machine learning approaches, and FM is a hybrid machine learning approach consisting of GRNN, BPNN, and ELM. The effectiveness of these machine learning methods in wind speed forecasting are fully investigated by one-year field monitoring data, and their performance is comprehensively compared.

• Spatial Information Research
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• 제18권3호
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• pp.13-22
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• 2010

최근 이상기후로 인한 강풍 및 태풍이 자주 발생하여 많은 인적, 물적 피해가 발생함에 따라 구조물 설계 시 적용하는 풍하중 산정에 관한 연구의 중요성이 강조되고 있다. 지형에 따른 풍속지형계수의 증가는 풍속의 증가를 의미하며 풍속의 증가는 제곱에 비례하여 풍하중에 영향을 미치기 때문에 풍속지형계수 산정을 위한 지리정보를 정확하게 측정하는 것이 필요하다. 따라서, 본 연구에서는 BIM(Building Information Modeling) 프로그램인 ArchiCAD를 이용하여 정확하고 합리적인 풍속지형계수 산정 방법을 제시하고자 한다. 풍하중을 고려한 구조물 설계 시 본 연구에서 제안한 방법을 이용함으로서 설계의 합리성과 경제성을 더 높일 수 있을 것이다.

• 신재생에너지
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• 제9권1호
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• pp.12-16
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• 2013

The nacelle anemometer mounted behind the blade roots of a wind turbine measures distorted wind speed comparable with free-stream wind because of the wake effects caused dependent upon the operation of the wind turbine and the rotation of its blades. The field campaign was carried out to measure free-stream wind speed at a height identical to the height of the nacelle anemometer by deploying a ground-based remote-sensing equipment, LIDAR. It is derived that a third-order polynomial equation for correcting wind speed measured by the nacelle anemometer to undistorted free-stream wind speed incident to a wind turbine. It is anticipated that the derived correction equation enables wind speed measured by the nacelle anemometer to be used as a precise input for a wind turbine performance test and for developing an active control logic.

• Wind and Structures
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• 제17권4호
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• pp.419-433
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• 2013

This paper investigates the vertical profiles of horizontal mean wind speed and direction based on the synchronized measurements from a Doppler radar profiler and an anemometer during 16 tropical cyclones at a coastal site in Hong Kong. The speed profiles with both open sea and hilly exposures were found to follow the log-law below a height of 500 m. Above this height, there was an additional wind speed shear in the profile for hilly upwind terrain. The fitting parameters with both the power-law and the log-law varied with wind strength. The direction profiles were also sensitive to local terrain setups and surrounding topographic features. For a uniform open sea terrain, wind direction veered logarithmically with height from the surface level up to the free atmospheric altitude of about 1200 m. The accumulated veering angle within the whole boundary layer was observed to be $30^{\circ}$. Mean wind direction under other terrain conditions also increased logarithmically with height above 500 m with a trend of rougher exposures corresponding to lager veering angles. A number of empirical parameters for engineering applications were presented, including the speed adjustment factors, power exponents of speed profiles, and veering angle, etc. The objective of this study aims to provide useful information on boundary layer wind characteristics for wind-resistant design of high-rise structures in coastal areas.