• 제어로봇시스템학회논문지
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• 제15권12호
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• pp.1157-1162
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• 2009

The aerodynamic torque and power caused by the interaction between the wind and blade of wind turbine are highly nonlinear. For this reason, the overall dynamic behaviors of wind turbine have nonlinear characteristics. The aerodynamic nonlinearity also affects properties of torque control for wind turbine. In this paper, the nonlinear aerodynamic property according to the wind speed below rated power and its effects on the torque control system are investigated. Nonlinear parameter representing change of aerodynamic torque with respect to rotor speed is obtained by linearization technique. Effects of this aerodynamic nonlinear parameter on the closed-loop torque system with PI controller for an 1.5 MW wind turbine are presented.

• 한국유체기계학회 논문집
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• 제15권2호
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• pp.30-35
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• 2012

Aerodynamic torque of wind turbine has nonlinear properties. Nonlinearity of aerodynamic torque is very important in wind turbine in the aspect of control. The traditional torque control method using optimal mode gain has been applied in many wind turbines but its response is slower as wind turbine size is larger. In this paper, a torque control method using a nonlinear parameter of rotor speed among nonlinear properties of aerodynamic torque. Simulink model is implemented to obtain the nonlinear parameter of rotor speed and numerical simulations for a 2MW wind turbine are carried out and simulation results for the traditional and proposed torque control methods are compared.

• 한국유체기계학회 논문집
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• 제16권6호
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• pp.5-11
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• 2013

Torque control methods of wind turbine are mainly classified into two methods: torque-mode and speed-mode methods. The traditional torque-mode method, in which generator torque proportional to square of generator speed is determined, has been chosen in many wind turbines but its response is slower as they are larger in multi-MW size. Torque control methods based on both speed-mode and torque-mode can be used to make response of wind turbine faster. In this paper, two torque control methods based on the traditional torque-mode method are applied to a 2.75 MW wind turbine. It is shown through some simulation results for real turbulence wind speeds that torque control method based on torque-mode has the merit of reducing fluctuations of generated power than PI controller based on speed-mode.

• Wind and Structures
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• 제21권4호
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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.

• Journal of Power Electronics
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• 제11권3호
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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.

• 한국유체기계학회 논문집
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• 제15권2호
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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.

• 대한기계학회논문집B
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• 제33권11호
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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.

• 대한기계학회논문집A
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• 제34권12호
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• pp.1885-1891
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• 2010

풍력터빈의 토크제어는 정격풍속 이하에서 매우 중요하다. 토크제어의 주된 목적은 바람이 가진 공기역학적 파워로부터 최대의 파워를 얻도록 하는 것이다. 풍력터빈의 토크제어 방법은 토크모드 제어와 속도모드 제어로 크게 두 경우로 구분된다. 토크모드 제어는 풍력터빈에서 잘 알려지고 전통적으로 사용되는 방법으로 발전기 회전속도의 제곱에 비례하도록 발전기의 토크크기를 발생시킨다. 속도모드 제어에서는 발전기의 토크크기를 발생하기 위하여 PI 제어기를 사용한다. 본 논문에서는 실제 풍속이 난류인 점을 고려하여 2.75 MW 풍력터빈을 대상으로 두 토크제어 방법을 적용한 수치실험 결과를 제시하고 응답특성을 비교한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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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.

• 한국항공우주학회지
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• 제35권10호
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• pp.891-898
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• 2007

피치 제어형 수평축 풍력터빈에 대한 공력최적 설계 형상과 피치 변화에 따른 공력 성능 특성을 수치적으로 계산하였다. 수치적 방법은 날개 요소이론을 적용하였으며, Prandtl의 팁 손실 효과, 에어포일의 분포 효과, 후류의 회전 효과 등을 고려하였다. 블레이드 설계에는 총 6개의 서로 다른 에어포일을 사용하였으며, 구조적 강성을 갖기 위해서 허브 측에는 최대 40% 두께비의 에어포일을 분포시켰다. 최적 설계에서 얻어진 비선형 코드 길이는 제작성과 무게 등을 고려하여 선형화 시켰고, 선형화에 따른 공력성능 변화는 무시할만하다는 결과를 얻어내었다. 피치각 변화에 따른 동력성능, 추력성능, 토크 성능 곡선을 비교한 결과 $3^{\circ}$의 피치각 변화에도 민감한 공력 값의 변동이 생김을 알 수 있었고, 정밀한 피치 제어를 위한 각도 제어는 증분이 $3^{\circ}$보다 작은 값으로 피치 제어 알고리즘과 피치 구동 장치가 필요함을 알 수 있었다. 또한 최대 토크는 설계속도비보다 작은 속도비에서 발생되는 결과를 보여주었다.