• Title/Summary/Keyword: Aerodynamic Torque

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An integrator based wind speed estimator for wind turbine control

  • Elmaati, Younes Ait;El Bahir, Lhoussain;Faitah, Khalid
    • Wind and Structures
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    • v.21 no.4
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    • pp.443-460
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    • 2015
  • In this paper, an integrator based method to estimate the effective wind speed in wind turbine systems is proposed. First, the aerodynamic torque was accurately estimated through a proportional gain based observer where the generator speed is the measured output of the system. The torque signal contains not only useful frequencies of the wind, but also high frequencies and the ones due to structural vibration. The useful information of the wind signal is low frequency. A spectral analysis permitted the determination of the useful frequencies. The high frequencies were then filtered before introducing the torque signal in the wind speed observer. The desired effective wind speed was extracted through an integrator based observer using the previously estimated aerodynamic torque. The strength of the method is to avoid numerical solutions used in literature of the wind speed estimation. The effectiveness of the proposed wind speed estimator and its use to control the generator speed has been tested under turbulent situations using the FAST software (Fatigue, Aerodynamics, Structures, and Turbulence), for large scale Megawatt turbine.

Optimal Aerodynamic Design and Performance Analysis for Pitch-Controlled HAWT (가변 피치형 수평축 풍력 터빈의 공력 최적설계 및 피치제어 성능 연구)

  • Ryu, Ki-Wahn
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.35 no.10
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    • pp.891-898
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    • 2007
  • Optimal aerodynamic design for the pitch-controlled horizontal axis wind turbine and its aerodynamic performance for various pitch angles are performed numerically by using the blade element momentum theory. The numerical calculation includes effects such as Prandtl‘s tip loss, airfoil distribution, and wake rotation. Six different airfoils are distributed along the blade span, and the special airfoil i.e. airfoil of 40% thickness ratio is adopted at the hub side to have structural integrity. The nonlinear chord obtained from the optimal design procedure is linearized to decrease the weight and to increase the productivity with very little change of the aerodynamic performance. From the comparisons of the power, thrust, and torque coefficients with corresponding values of different pitch angles, the aerodynamic performance shows delicate changes for just $3^{\circ}$ increase or decrease of the pitch angle. For precisive pitch control, it requires the pitch control algorithm and its drive mechanism below $3^{\circ}$ increment of pitch angle. The maximum torque is generated when the speed ratio is smaller than the designed one.

A Instantaneous Torque Analysis of the Darrieus Wind Turbine varying with the rotating Angle of blade (다리우스 풍차의 회전각에 따른 순간 토오크 해석)

  • Oh, Chul-Soo;Kwon, Soon-Hong
    • Proceedings of the KIEE Conference
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    • 1992.07b
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    • pp.659-661
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    • 1992
  • This paper deals with aerodynamic problems of the rotating blade of Darrieus wind turbine and its instantaneous torque. The instantaneous torque varying with the rotating angle of blade was obtained through resultant wind velocity, angle of attack, lift and drag coefficient. These are obtained from a given wing section, size and wind velocity.

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Performance Improvement of a Polygon Mirror Scanner Motor for Laser Beam Printer (레이저빔프린터용 폴리곤 미러 스캐너 모터의 특성개선)

  • You, Yong-min
    • Proceedings of the KIEE Conference
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    • 2015.07a
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    • pp.854-855
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    • 2015
  • Electric machines for office automation device such as printer and scanner have been required the low noise and vibration performance. Many researches about the low noise and vibration of polygon mirror scanner motor have been also progressed. The noise and vibration of polygon mirror scanner motor can be classified by aerodynamic, structural and electromagnetic. Electromagnetic noise and vibration can be occurred by high cogging torque and nonsinusoidal back EMF. To improve the cogging torque and back EMF characteristic, we apply unequal air-gap. To analyse characteristic of a polygon mirror scanner motor, two dimensional finite element method is used. To minimize the cogging torque of a polygon mirror motor, Kriging based on latin hypercube sampling (LHS) is utilized. As a result, the cogging torque and torque ripple improved while maintaining the back EMF and average torque.

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An Effect of Pitch Gain-Scheduling on Shaft Vibration Response of Wind Turbine (풍력터빈 축 진동 응답에 대한 피치 게인-스케쥴링의 효과)

  • Lim, Chae-Wook;Jo, Jun-Chul
    • The KSFM Journal of Fluid Machinery
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    • v.15 no.2
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    • pp.36-40
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    • 2012
  • Pitch control of wind turbine is activated above rated wind speed for the purpose of rated power regulation. When we design pitch controller, its gain-scheduling is essential due to nonlinear characteristics of aerodynamic torque. In this study, 2-mass model including a vibration mode of drive-train for a 2 MW wind turbine is considered and pitch control with gain-scheduling using a linearization analysis of the nonlinear aerodynamic torque is applied. Some simulation results for the pitch gain-scheduling under step wind speed are presented and investigated. It is shown that gain-scheduling in pitch control is important especially in the region of high wind speeds when there exists a vibration mode of drive-train.

A Method to Define Steady-State Curves for Variable-Speed Variable-Pitch Wind Turbine (가변속도-가변피치 풍력터빈의 정상상태 곡선 결정 방법)

  • Lim, Chae-Wook
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.11
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    • pp.894-899
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    • 2009
  • Aerodynamic power and torque of wind turbine are highly nonlinear and its operation mode depends on control strategies. Therefore, it is essential to define steady-state curves for the purpose of control and operation of wind turbine system. The steady-state curves of wind turbine can be defined by determining its operating points. In this paper, an algorithm to determine operating points of variable-speed variable-pitch wind turbine is presented on the basis of pitch-to-feather control strategy. And this algorithm is applied to obtain steady-state curves for an 1.5MW wind turbine.

Aeroelastic Stability Analysis of Composite Bearingless Rotor Blades in Hover (복합재 무베어링 로우터 블레이드의 정지 비행시 공력탄성학적 안정성 해석)

  • Lim In-Gyu;Choi Ji-Hoon;Lee In;Han Jae-Hung
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2004.04a
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    • pp.83-86
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    • 2004
  • The aeroelastic stability analysis of composite bearingless rotors is investigated using a large deflection beam theory in hover. The bearingless rotor configuration consists of a single flexbeam with a wrap-around type torque tube and the pitch links located at the leading edge and trailing edge of the torque tube root. For the analysis of composite bearingless rotors, flexbeam is assumed to be a rectangular section made of laminate. Two-dimensional quasi-steady strip theory and Loewy's aerodynamic theory with the lift deficiency function are used for unsteady aerodynamic computation. The finite element equations of motion for beams are obtained using Hamilton's principle. Numerical results of selected bearingless rotor configurations are obtained for the lay-up of laminae in the flexbeam and pitch links location.

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Aerodynamic Design of Slim and High-efficient Turbo-Fan (박판형 고효율 터보홴의 공력학적 설계)

  • Lee, Myeong-Jae;Kim, Nam-Uk;Park, Duck-Jun;Cho, In-Soo;Lee, Seung-Bae
    • Proceedings of the KSME Conference
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    • 2008.11b
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    • pp.2600-2605
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    • 2008
  • Turbo-fans for a FFU unit should be aerodynamically designed to provide the FFU system with the given flow-rate at the lowest rotational-speed by considering the interaction effect with the FFU casing. In this study, slim and highly efficient turbo-fans are designed to satisfy the given performance at the specific speed by using the hybrid-stacking method of an inducer and a 2D-bladed turbo fan. The mean-line analysis, cascade theory, and CFD technique are all together applied to control the passage areas on the meridional plane from the inlet to the exit of the blade. Furthermore, the torque control algorithm is adopted to improve the performances within the constraints by the motor rpm-torque characteristics, and the resulting measured performances of mock-up fans are discussed.

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Wind-Tunnel Investigation for the Aerodynamic Characteristics of Electro-Optical Targeting System (풍동시험을 통한 전자광학 추적장치의 공력특성 연구)

  • Lee, Sang-Il;Lee, Jae-Won;Yee, Kwan-Jung;Oh, Se-Jong;Jung, Hyeone-Seok;Kim, Dae-Jin
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.3
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    • pp.240-247
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    • 2009
  • Wind tunnel test for Electro-Optical Targeting System(EOTS) has been conducted to investigate the aerodynamic characteristics, especially the torque characteristics of the rotating parts to insure the enough actuator power during the actual operation. The influence of EOTS's complex configuration, such as the observation window, has been investigated by comparing with the results of the simplified models made of half sphere and the cylinder. It has been found that the position of the observation window of EOTS has an effect on surface pressure distribution and the torque characteristics of the rotating observation part.

Sliding Mode Controller for Torque and Pitch Control of PMSG Wind Power Systems

  • Lee, Sung-Hun;Joo, Young-Jun;Back, Ju-Hoon;Seo, Jin-Heon;Choy, Ick
    • Journal of Power Electronics
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    • v.11 no.3
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    • pp.342-349
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    • 2011
  • We propose a torque and pitch control scheme for variable speed wind turbines with permanent magnet synchronous generator (PMSG). A torque controller is designed to maximize the power below the rated wind speed and a pitch controller is designed to regulate the output power above the rated wind speed. The controllers exploit the sliding mode control scheme considering the variation of wind speed. Since the aerodynamic torque and rotor acceleration are difficult to measure in practice, a finite time convergent observer is designed which estimates them. In order to verify the proposed control strategy, we present stability analysis as well as simulation results.