• Wind and Structures
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• 제34권3호
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• pp.291-301
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• 2022

Although mostly used in wind turbine market, single rotor wind turbines have problems with transportation and installation costs due to their large size. In order to solve such problems, multi-rotor wind turbine is being proposed; however, light weight design of multi-rotor wind turbine is required considering the installation at offshore or deep sea. This study proposes the systematic design process of the multi-rotor wind turbine focused on its supporting structure with simultaneous consideration of static and dynamic behaviors in an ideal situation. 2D and successive 3D topology optimization process based on the density method were applied to minimize the compliance of supporting structure. To realize the conceptual design obtained by topology optimization for manufacturing feasibility, the derived 3D structure was modified to have shell structures and optimized again through parametric design using the design of experiments and the response surface method for detail design of their thicknesses and radii. The resultant structure was determined to satisfy the stress and the buckling load constraint as well as to minimize the weight and the resultant supporting structure were verified numerically.

• 한국정밀공학회지
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• 제27권9호
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• pp.26-33
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• 2010

A multi-MW wind turbine is a huge mechanical structure, of which the rotor diameter is more or less than 100 m. Rotor blades experience unsymmetric mechanical loads caused by the interaction of incoming wind with the tower and wind shear effect. These mechanical loads are transferred to the entire structure of the wind turbine and are known as the major reasons for shortening the life span of the wind turbine. Therefore, as the size of wind turbine gets bigger, the mitigation of mechanical loads becomes more important issue in wind turbine control system design. In this paper, a concept of an individual pitch control(IPC), which minimizes the mechanical loads of rotor blades, is introduced, and simulation results using IPC are discussed.

• 한국유체기계학회 논문집
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• 제19권6호
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• pp.14-18
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• 2016

Multi-MW wind turbines have very large blades over 40~50 m in length. Some factors like wind shear and tower shadow make an effect on asymmetric loads on the blades. Larger asymmetric loads are produced as the length of blade is getting longer. In this paper, a 2 MW on-shore wind turbine is considered and variations of thrust on 3 blades and rotor hub under wind shear are calculated by using a commercial Bladed S/W and dynamic properties of the thrust variations are investigated. It is shown that the amplitude of the asymmetric thrust on each blade under wind shear is getting larger as the wind speed increases, the frequency of the thrust variation on each blade is same as the one of rotor speed, and the frequency of the thrust variation at rotor hub is 3 times as high as the one of rotor speed.

• 대한기계학회논문집B
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• 제38권4호
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• pp.289-309
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• 2014

풍력터빈 블레이드는 바람의 운동에너지를 기계적 에너지로 변환하는 장치로써 풍력발전시스템의 출력성능, 에너지변환효율, 하중 및 동적 안정성에 영향을 미칠 수 있기 때문에 주요부품으로 분류된다. 따라서 최적의 블레이드 설계결과를 얻기 위해서는 시스템 특성이 고려된 공력-구조 통합설계가 중요하다. 본 연구에서는 풍력터빈 시스템과의 상호작용이 고려된 블레이드 설계절차를 제안하였고, 2 MW 급 블레이드(KR40.1b)의 공력-구조 통합 설계결과를 제시하였다. 또한 전술한 바와 같이 로터 블레이드에 작용하는 극한하중 및 피로하중은 시스템 운전조건에 따라 가변적이므로 시스템통합하중해석을 위한 2 MW 풍력발전시스템 모델링을 수행하였으며, IEC 61400-1 및 (사)한국선급의 풍력발전기술기준에 따라 수행된 하중해석결과를 제시하였다.

• 전력전자학회논문지
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• 제9권1호
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• pp.1-9
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• 2004

본 논문에서는 로터 블레이드, 발전기, 로터 블레이드와 발전기에 연결된 고/저속 회전축 및 회전축간의 회전력을 전달하는 기어 시스템 등 다수의 몸체가 서로 상대적인 운동이 가능한 채 연결되어 있는 단일로터 수평축 풍력발전 시스템을 다몸체 시스템으로 간주한 후, 다몸체 역학을 이용한 풍력발전 시스템 모델링 기법을 제안하였다. 이를 기반으로 풍력발전 시스템의 성능 해석을 위한 시뮬레이터를 개발하였다. 그리고 다양한 시뮬레이션을 통해 제안된 풍력발전 시스템 모델링 기법과 시뮬레이터의 타당성을 검증하였다.

• 한국태양에너지학회 논문집
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• 제34권1호
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• pp.1-7
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• 2014

A study on the available power of a wind turbine to be used for wind farm control was performed in this study, To accurately estimate the available power it is important to obtain a suitable wind which represents the three dimensional wind that the wind turbine rotor faces and also used to calculate the power. For this, two different models, the equivalent wind and the wind speed estimator were constructed and used for dynamic simulation using matlab simulink. From the comparison of the simulation result with that from a commercial code based on multi-body dynamics, it was found that using the hub height wind to estimate available power from a turbine results in high frequency components in the power prediction which is, in reality, filtered out by the rotor inertia. It was also found that the wind speed estimator yielded less error than the equivalent wind when compared with the result from the commercial code.

• 한국항공우주학회지
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• 제33권7호
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• pp.40-50
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• 2005

본 논문에서는 이중 로터 풍력 발전 시스템에 대한 모델링 및 성능 예측 결과를 제시하였다. 공력 모델은 블레이드 요소 및 모멘텀 이론에 근거하였으며, 시스템 동역학 모델은 다몸체 역학을 적용하였다. 이중 로터 풍력 발전 시스템의 정상 상태는 물론 이중 여자 유도 발전기를 탑재한 발전 시스템에 대하여 풍속 변화에 따른 과도 응답을 분석하였고, 로터 회전수 및 발전 출력 제어를 위하여 주 및 보조 로터의 피치각 제어 전략의 도출 및 비선형 시뮬레이션 결과를 제시하였다.

• Journal of Power Electronics
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• 제11권2호
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• pp.211-217
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• 2011

The dynamic response of a multi-MW wind turbine to a sudden change in wind speed is usually slow, because of the slow pitch control system. This could cause a large excursion of the rotor speed and an output power over the rated. A feedforward pitch control can be applied to minimize the fluctuations of these parameters. This paper introduces the complete design steps for a feedforward pitch controller, which consist of three stages, i.e. the aerodynamic torque estimation, the 3-dimensional lookup table for the wind seed estimation, and the calculation of the feedforward pitch amount. The effectiveness of the feedforward control is verified through numerical simulations of a multi-MW wind turbine.

• 한국소음진동공학회논문집
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• 제19권7호
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• pp.651-658
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• 2009

In this study, computer applied engineering(CAE) techniques are fully used to efficiently conduct structural and dynamic analyses of a huge composite rotor blade using super-element. Computational fluid dynamics(CFD) is used to predict aerodynamic loads of the rotating wind-turbine blade. Structural vibration analysis is conducted based on the non-linear finite element method for composite laminates and multi-body dynamic simulation tools. Various numerical results are presented for comparison and the structural dynamic behaviors of the rotor blade are investigated herein.

• 한국유체기계학회 논문집
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• 제11권4호
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• pp.22-31
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• 2008

In this study, computer applied engineering (CAE) techniques are fully used to conduct structural and dynamic analyses of a huge composite rotor blade. Computational fluid dynamics is used to predict aerodynamic load of the rotating wind-turbine blade model. Static and dynamic structural analyses are conducted based on finite element method for composite laminates and multi-body dynamic simulation tools. Various numerical results for aerodynamic load, static stress, buckling and dynamic analyses are presented and characteristics of structural behaviors are investigated herein.