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동심원 등가풍속을 이용한 대기안정도에 따른 풍력자원 변화에 관한 연구
류건화(Geon-Hwa Ryu),김동혁(Dong-Hyeok Kim),이화운(Hwa-Woon Lee),박순영(Soon-Young Park),유정우(Jung-Woo Yoo),김현구(Hyun-Goo Kim) 한국태양에너지학회 2016 한국태양에너지학회 논문집 Vol.36 No.1
The power production using hub height wind speed tends to be overestimated than actual power production. It is because the hub height wind speed cannot represent vertical wind shear and blade tip loss that aerodynamics characteristic on the wind turbine. The commercial CFD model WindSim is used to compare and analyze each power production. A classification of atmospheric stability is accomplished by Monin-Obukhov length. The concentric wind speed constantly represents low value than horizontal equivalent wind speed or hub height wind speed, and also relevant to power production. The difference between hub height wind speed and concentric equivalent wind speed is higher in nighttime than daytime. Under the strongly convective state, power production is lower than under the stable state, especially using the concentric equivalent wind speed. Using the concentric equivalent wind speed considering vertical wind shear and blade tip loss is well estimated to decide suitable area for constructing wind farm.
Shuting Wan,Lifeng Cheng,Xiaoling Sheng 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.2
The effects of wind shear and the tower shadow contribute to periodic fluctuations in the wind speed and aerodynamic torque, which cause several problems. This study develops an equivalent wind speed model for large-scale, n-bladed wind turbines that includes the wind shear and the tower shadow effects. The comprehensive model is used to derive the disturbance components of wind speed caused by wind shear, the tower shadow, their synthesis, and the equivalent wind speed and to delineate their spatial distributions in the rotor disk area. Simulation results reveal that the effects of wind shear, the tower shadow, and the equivalent wind speed on the disturbance components fluctuate periodically and are closely related to the wind turbine correlation parameters, such as the rotor radius, hub center height, tower radius, distance from the tower midline to the blade, wind shear exponent, and blade number.
강보신,투멘바야르 운다르마,고경남 한국풍력에너지학회 2021 풍력에너지저널 Vol.12 No.4
An experimental investigation was carried out to identify the difference between wind turbine power curves derived from hub height wind speed (HHWS) and rotor equivalent wind speed (REWS) at the Haengwon and Dongbok wind farms on Jeju Island. The terrains of the wind farms were analyzed according to International Electrotechnical Commission (IEC) 61400-12-1 2nd edition. The Haengwon wind farm was analyzed as a simple terrain, while the Dongbok wind farm was analyzed as a complex terrain that needed site calibration before power performance testing. Since the site calibration process for the operating wind farm was not possible, power performance testing was performed without site calibration. The power curves were derived using HHWS and REWS, and the annual energy productions (AEPs) were calculated by applying the Rayleigh wind speed distribution to the power curves. In addition, the normalized revenue by 1 MW for 20 years was calculated using the AEPs. As a result, the average HHWS and REWS at the Haengwon wind farm were 11.68 m/s and 11.64 m/s, while those at the Dongbok wind farm were 8.22 m/s and 8.18 m/s, respectively. The average relative error of the AEP at annual average wind speeds of 5to 11 m/s was 0.96 % for Haengwon wind farm and 1.68 % for the Dongbok wind farm. The average revenue difference at annual average wind speeds of 4 to 11m/s was 55 million Korean won for the Haengwon wind farm and 111 million Korean won for the Dongbok wind farm.
CFD를 이용한 등가풍속 산정과 대기안정도에 따른 연안풍력단지 발전량 변화 연구
류건화 ( Geon Hwa Ryu ),김동혁 ( Dong Hyeok Kim ),이화운 ( Hwa Woon Lee ),박순영 ( Soon Young Park ),김현구 ( Hyun Goo Kim ) 한국환경과학회 2016 한국환경과학회지 Vol.25 No.2
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 (α). AEP is increased by 11% when atmosphere becomes to be stabilized (α > 0.2) than it is convective (α < 0.1). However, it is found that extreme wind shear (α > 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.
Mingjin Zhang,Jinxiang Zhang,Junting Long,Yongle Li,Yulin Zou,Dianguo Yin 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.12
Due to the complexity and changeability of the wind field in deep-cut gorges, the vehicles on the bridge deck are easily affected by a strong crosswind. Thus, to accurately evaluate the wind field characteristics of a suspension bridge deck, the wind profiles of wind speed and angle of attack (AoA) and the vehicle aerodynamic parameters were investigated by the CFD. The results show that the shape of wind speed profile is mainly controlled by the AoA but less affected by the Reynolds number. The main girder's shielding effect can accelerate the local wind field, and the closer to the windward lane, the less the interference; thus, a suitable location of measuring points to represent the incoming flow is found. Furthermore, the equivalent wind speed based on the equivalent side force is generally larger than the value based on the rolling moment, and the responding value is greatly affected by the AoA. In addition, the vortex is a time-dependent phenomenon, the averaged flow field produced less force in the wake, but the high local wind speed variations may affect the traffic unfavorably. The results provide an essential reference significance for studying the local wind field characteristics of the bridge deck.
신동헌,고경남,강민상,유동훈,강문종,김현식 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.4
To clarify the difference in the wind turbine power curves obtained by cup anemometer and light detection and ranging (LIDAR) measurements, an investigation was experimentally performed in the Haengwon wind farm on Jeju Island, South Korea. A LIDAR mounted on the nacelle of a 1.5-MW test wind turbine was used with a met mast and a ground LIDAR positioned at a distance of 2.5 times the rotor diameter from the turbine. The wind speed data obtained by each instrument were compared through linear regression analysis. The rotor equivalent wind speed (REWS) was derived from a cup anemometer and ground LIDAR measurements in accordance with the International Electrotechnical Commission (IEC) standard 61400-12-1, 2nd edition. The scatter plots were drawn using the wind data measured by each instrument and compared in terms of the standard deviation. The power curves drawn from the REWS and nacelle LIDAR measurements were compared with that from the cup anemometer measurements according to IEC 61400-12-1, 1st edition. To quantitatively identify the difference in the power curves, the relative error was calculated using the cup anemometer power curve as a reference. Consequently, the relative error for the power output in the bin interval of 0.5 m/s before the rated wind speed was high, whereas that after the rated was close to 0 %. The relative errors for the power curve from the REWS and the nacelle LIDAR measurements were -0.37 % and 3.01 % on average, respectively.
우리나라 비중앙급전발전기의 하루전 출력 예측시스템 개발
이연찬(Yeon-chan Lee),임진택(Jin-taek Lim),오웅진(Ung-jin Oh),Duy-Phuong N.Do,최재석(Jae-seok Choi),김진수(Jin-su Kim) 대한전기학회 2015 전기학회논문지 Vol.64 No.4
This paper proposes a probabilistic generation assessment model of renewable energy generators(REGs) considering uncertainty of resources, mainly focused on Wind Turbine Generator(WTG) and Solar Cell Generator(SCG) which are dispersed widely in South Korea The proposed numerical analysis method assesses the one day-ahead generation by combining equivalent generation characteristics function and probabilistic distribution function of wind speed(WS) and solar radiation(SR) resources. The equivalent generation functions(EGFs) of the wind and solar farms are established by grouping a lot of the farms appropriately centered on Weather Measurement Station(WMS). First, the EGFs are assessed by using regression analysis method based on typical least square method from the recorded actual generation data and historical resources(WS and SR). Second, the generation of the REGs is assessed by adding the one day-ahead resources forecast, announced by WMS, to the EGFs which are formulated as third order degree polynomials using the regression analysis. Third, a Renewable Energy Generation Assessment System(REGAS) including D/B of recorded actual generation data and historical resources is developed using the model and algorithm predicting one day-ahead power output of renewable energy generators.