• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.261-264
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• 2006

This paper describes the effects to wind turbine blade aerodynamics due to interaction between blade and tower on upwind type HAWT. In order to analyze effects of blade-tower interact ion, the analyst s program WINFAS which is based on VLM(Vortex Lattice Method), Free wake and FVE model is used. In this study, the changes of wind turbine blade aerodynamics caused by blade-tower interact ion are Investigated with various parameters windshear, yaw error, TSR and tower diameter.

• New & Renewable Energy
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• v.2 no.4 s.8
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• pp.19-26
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• 2006

Tower shell design is very important because tower takes about 20% of overall wind turbine cost. This paper contains procedure of tower analysis and tower shell thickness optimization concept. Some of requirements like eigenfrequency and buckling evaluated by numerical method. But strength and fatigue can be derived by mathematical method simply. Using this procedure, tower shell thickness can be designed without repetition of complicated calculation.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.192-194
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• 2007

This paper proposes a new wind turbine simulator using a squirrel cage induction for control performance test of DFIG (doubly-fed induction generator). The turbine static characteristics are modeled using the relation between the turbine torque versus the wind speed and the blade pitch angle. The turbine performance is subjected to a real wind speed pattern by modeling the wind speed as a sum of harmonics with a wide range of frequency. The turbine model includes the effect of the tower shadow and wind shear. A pitch angle controller is designed and used to protect the coupled generator by limiting the turbine speed to the maximum value. Experimental results are provided for a 3[kW] wind turbine simulator at laboratory.

• Wind and Structures
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• v.17 no.6
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• pp.589-608
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• 2013

A model is proposed to analyse the along-wind dynamic response of upwind turbines with horizontal axis under service wind conditions. The model takes into account the dynamic coupling effect between rotor blades and supporting tower. The wind speed field is decomposed into a mean component, accounting for the well-known wind shear effect, and a fluctuating component, treated through a spectral approach. Accordingly, the so-called rotationally sampled spectra are introduced for the blades to account for the effect of their rotating motion. Wind forces acting on the rotor blades are calculated according to the blade element momentum model. The tower shadow effect is also included in the present model. Two examples of a large and medium size wind turbines are modelled, and their dynamic response is analysed and compared with the results of a conventional static analysis.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.2
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• pp.209-215
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• 2010

In this study, seismic response analyses of a MW class wind-turbine have been conducted considering applied wind-loads using advanced computational method based on CFD and FEM. Typical lateral and vertical acceleration levels induced by earthquake is also considered herein. Practical numerical method for seismic response analysis of wind-turbine tower models are presented in the time-domain and the effects of wind load and seismic excitation for responses are compared to each other. It is importantly shown that possible earthquake effect during typical operating conditions should be taken into account in the design of huge wind-turbine tower systems because of its enormous inertia characteristics for induced maximum stress level.

• Wind and Structures
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• v.22 no.5
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• pp.525-541
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• 2016

An offshore wind turbine supported by a spar buoy floating platform is the subject of this study on tower and rotor extreme loads. The platform, with a 120-meter draft and assumed to be sited in 320 meters of water, supports a 5 MW wind turbine. A baseline model for this turbine developed at the National Renewable Energy Laboratory (NREL) is employed in stochastic response simulations. The support platform, along with the mooring system consisting of three catenary lines, chosen for loads modeling, is based on the "Hywind" floating wind turbine concept. Our interest lies in gaining an understanding of the dynamic coupling between the support platform motion and the turbine loads. We first investigate short-term response statistics using stochastic simulation for a range of different environmental wind and wave conditions. From this study, we identify a few "controlling" environmental conditions for which long-term turbine load statistics and probability distributions are established.

• Wind and Structures
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• v.30 no.6
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• pp.663-678
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• 2020

Robust semi-active vibration control of wind turbines using tuned mass dampers (TMDs) is a promising technique. This study investigates a 1.5 megawatt wind turbine controlled by eight different types of tuned mass damper systems of equal mass: a passive TMD, a semi-active varying-spring TMD, a semi-active varying-damper TMD, a semi-active varying-damper-and-spring TMD, as well as these four damper systems paired with an additional smaller passive TMD near the mid-point of the tower. The mechanism and controllers for each of these TMD systems are explained, such as employing magnetorheological dampers for the varying-damper TMD cases. The turbine is modelled as a lumped-mass 3D finite element model. The uncontrolled and controlled turbines are subjected to loading and operational cases including service wind loads on operational turbines, seismic loading with service wind on operational turbines, and high-intensity storm wind loads on parked turbines. The displacement and acceleration responses of the tower at the first and second mode shape maxima were used as the performance indicators. Ultimately, it was found that while all the semi-active TMD systems outperformed the passive systems, it was the semi-active varying-damper-and-spring system that was found to be the most effective overall - capable of controlling vibrations about as effectively with only half the mass as a passive TMD. It was also shown that by reducing the mass of the TMD and adding a second smaller TMD below, the vibrations near the mid-point could be greatly reduced at the cost of slightly increased vibrations at the tower top.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.9-12
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• 2005

In this paper. we offer a new monitoring system that controls all of the windfar. it can also apply use general wind turbine systems and real meteorological tower. We propose a hierarchical releiable monitoring system connected by wireless communication channels between monitoring host computer and modular slave measuring subsystems. Our system has two hierarchical subsystems: slave measuring systems, and supervisory host computer. We design and implement that the slave measuring subsystems is placed in meteorological tower and wind turbines, and the supervisory host computer in safety zone, The micro-controller in slave measuring system is duplicated using cold-standby method for reliability. The host computer and slave system constructs a feedback system, with wireless communication channel between them. For monitoring and command function, the supervisory computer is implemented with a Personal Computer using graphic user interface. Consequently. we can get a reliable but economic system.

• Smart Structures and Systems
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• v.26 no.4
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• pp.435-449
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• 2020

To effectively extract the vast wind resource, offshore wind turbines are designed with large rotor and slender tower, which makes them vulnerable to external vibration sources such as wind and wave loads. Substantial research efforts have been devoted to mitigate the unwanted vibrations of offshore wind turbines to ensure their serviceability and safety in the normal working condition. However, most previous studies investigated the vibration control of wind turbines in one direction only, i.e., either the out-of-plane or in-plane direction. In reality, wind turbines inevitably vibrate in both directions when they are subjected to the external excitations. The studies on both the in-plane and out-of-plane vibration control of wind turbines are, however, scarce. In the present study, the NREL 5 MW wind turbine is taken as an example, a detailed three-dimensional (3D) Finite Element (FE) model of the wind turbine is developed in ABAQUS. To simultaneously control the in-plane and out-of-plane vibrations induced by the combined wind and wave loads, another carefully designed (i.e., tuned) spring and dashpot are added to the perpendicular direction of each Tuned Mass Damper (TMD) system that is used to control the vibrations of the tower and blades in one particular direction. With this simple modification, a bi-directional TMD system is formed and the vibrations in both the out-of-plane and in-plane directions are simultaneously suppressed. To examine the control effectiveness, the responses of the wind turbine without control, with separate TMD system and the proposed bi-directional TMD system are calculated and compared. Numerical results show that the bi-directional TMD system can simultaneously control the out-of-plane and in-plane vibrations of the wind turbine without changing too much of the conventional design of the control system. The bi-directional control system therefore could be a cost-effective solution to mitigate the bi-directional vibrations of offshore wind turbines.

• The KSFM Journal of Fluid Machinery
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• v.18 no.1
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• pp.59-64
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• 2015

The pitch control system in wind turbines becomes more and more important as the wind turbines are larger in multi-MW size. PI controller has been applied in most pitch controllers and it has been known that gain-scheduling is essential for pitch control of wind turbines. A demo model of 2 MW wind turbine which represents the whole dynamics of wind turbine including dynamic behaviors of blade, tower and rotational shaft is given in the commercial Bladed S/W for real wind turbines. In this paper, some results on step responses of the pitch PI controller and effectiveness of gain-scheduled pitch PI controller are presented through the Bladed S/W for the 2 MW wind turbine.