• 전기전자학회논문지
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• 제22권2호
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• pp.460-475
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• 2018

In the variable-speed wind energy system, to achieve maximum power point tracking (MPPT), the wind turbine should run close to its optimal angular speed according to the wind speed. Non-linear control methods that consider the dynamic behavior of wind speed are generally used to provide maximum power and improved efficiency. In this perspective, the mechanical power is estimated using Kalman filter. And then, from the estimated mechanical power, the wind speed is estimated with Newton-Raphson method to achieve maximum power without anemometer. However, the blade shape and air density get changed with time and the generator efficiency is also degraded. This results in incorrect estimation of wind speed and MPPT. It causes not only the power loss but also incorrect wind resource assessment of site. In this paper, the adaptive maximum power point tracking control algorithm for wind turbine system based on the estimation of wind speed is proposed. The proposed method applies correction factor to wind turbine system to have accurate wind speed estimation for exact MPPT. The proposed method is validated with numerical simulations and the results show an improved performance.

• 한국유체기계학회 논문집
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• 제18권6호
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• pp.63-70
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• 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.

• 한국항공우주학회지
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• 제35권11호
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• pp.964-972
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• 2007

공기역학적으로 최대동력계수를 얻을 수 있도록 최적화된 블레이드를 장착한 수평축 풍력터빈 모델을 아음속 풍동에 장착하여 공력특성을 실험하였다. Upwind 방식과 downwind방식의 풍력 터빈 로터의 공력 특성을 비교하였을 때, 후자가 전자에 비해 측정토크의 교란이 더 크게 나타났으며, 이는 지지대에서 발생된 후류와 블레이드의 상호간섭이 원인으로 작용한다고 여겨진다. 블레이드 설치각이 0o인 경우에 설계 속도비 6에 해당하는 위치에서 최대 동력계수를 보여주고 있어 설계 조건을 잘 만족함을 알 수 있었다. 또한 음의 피치각 변화가 같은 값의 양의 피치각 변화에 비해 더 커다란 동력 감소가 발생되는 결과를 보여주었다.

• 동력기계공학회지
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• 제15권6호
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• pp.35-40
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• 2011

The present study aims at investigating the effect of the fluid-structure interaction on the aerodynamic performances in the turbo blower. The design specifications of the reference model driven by 400kW power were given as 7.43kg/s of mass flow rate, 1.66 of pressure ratio with 12000rpm of impeller rotating speed. Numerical simulation has been performed on the three cases based on the tip clearance between the impeller blade and the shroud. The CFX-turbo for flow fields and ANSYS-mechanical for structure domain were applied to solve the present FSI problems inside the turbo blower. Through the numerical results, the performances corrected by the FSI effects were proposed for the more reliable predictions.

• Journal of Advanced Marine Engineering and Technology
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• 제28권5호
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• pp.847-852
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• 2004

The wind turbine blade is the equipment converted wind into electric energy. The effect of the blade has influence of the output power and efficiency of wind turbine. The design of blade is considered of lift-to-drag ratio. structure. a condition of process of manufacture and stable maximum lift coefficient, etc. This study is used the simplified method for design of the aerodynamic blade and aerodynamic analysis used blade element method This Process is programed by delphi-language. The Program has any input values such as tip speed ratio blade length. hub length. a section of shape and max lift-to-drag ratio. The Program displays chord length and twist angle by input value and analyzes performance of the blade.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.391-392
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• 2010

본 논문에서는 조류발전 시스템의 시험을 위한 시뮬레이터를 구현하였다. 조류발전 시뮬레이터 모델은 회전자 모델, MPPT 알고리즘, 발전기 등을 포함하고 있으며 Matlab Simulink를 이용해 구현했다. 제안한 조류 발전용 시뮬레이터를 이용해 조류발전에서 주속비(Tip Speed Ratio) 제어방식의 출력 특성에 대한 시뮬레이션을 수행하여 그 타당성을 분석하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.650-655
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• 2001

Wind speeds can vary rapidly and wind turbines cannot easily follow these variations because of their inertia and aerodynamic characteristics. For maximum energy extraction. the turbine blades should operate at their optimum tip speed ratio, but with rapid changes in wind speed. this is usually not possible. To improve the energy extraction from turbulent wind, it is necessary to establish an effective measure of the high frequency component of the wind. and then to use this measure to optimise the operation of the turbine controller for maximum energy extraction. This paper presents an approach for combining readings from three anemometers into a composite wind speed measurement. and using this signal to control the operation of a permanent magnet generator to achieve maximum energy extraction. The method combines simulation and experimental investigations into a heuristic algorithm. and demonstrates its effectiveness with field trials.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.82-84
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• 1994

This paper presents a design of vertical axis Darrieus wind turbine for wind-power generating system. The wind turbine consists of two troposkien blades, diameter is 10m approximately, and chord length 380mm, tip ratio speed 4. The design of turbine is laid for the main data of rated wind speed 10m/s, turbine speed 78rpm, the generating power is estimated to 25kW, and this is contorted to commercial power line by means of three phase synchronous generator-inverter system.

• Wind and Structures
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• 제32권2호
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• pp.81-87
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• 2021

The aim of the current study is to compare the performance of large 2 MW and 3 MW wind turbines operating on existing onshore wind farms using Blade Element Momentum (BEM) theory and Angular Momentum (AM) theory and illustrate the performance characteristic curves of the turbines as a function of wind speed (U∞). To achieve this, the measurement data obtained from two different Wind Energy Power Plants (WEPPs) located in the Hatay region of Turkey was used. Two different horizontal-axis wind turbines with capacities of 2 MW and 3 MW were selected for evaluation and comparison. The hub-height wind speed (UD), turbine power output (P), atmospheric air temperature (Tatm) and turbine rotational speed (Ω) data were used in the evaluation of the turbine performance characteristics. Curves of turbine power output (P), axial flow induction factor (a), turbine rotational speed (Ω), turbine power coefficient (CP), blade tip speed ratio (λ), thrust force coefficient (CT) and thrust force (T) as a function of U∞ were obtained for the 2 MW and 3 MW wind turbines and these characteristic curves were compared. Results revealed that, for the same wind speed conditions, the higher-capacity wind turbine (3 MW) was operating at higher turbine power coefficient rates, while rotating at lower rotational speed ratios than the lower-capacity wind turbine (2 MW).

• Journal of Mechanical Science and Technology
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• 제14권7호
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• pp.752-763
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• 2000

The stress field around the dynamically propagating interface crack tip under a remote mixed mode loading condition has been studied with the aid of dynamic photoelastic method. The variation of stress field around the dynamic interface crack tip is photographed by using the Cranz-Shardin type camera having $10^6$ fps rate. The dynamically propagating crack velocities and the shapes of isochromatic fringe loops are characterized for varying mixed load conditions in double cantilever beam (DCB) specimens. The dynamic interface crack tip complex stress intensity factors, $K_1\;and\;K_2$, determined by a hybrid-experimental method are found to increase as the load mixture ratio of y/x (vertical/horizontal) values. Furthermore, it is found that the dynamically propagating interface crack velocities are highly dependent upon the varying mixed mode loading conditions and that the velocities are significantly small compared to those under the mode I impact loading conditions obtained by Shukla (Singh & Shukla, 1996a, b) and Rosakis (Rosakis et al., 1998) in the USA.