• KIEAE Journal
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• v.10 no.2
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• pp.63-69
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• 2010

Diverse problems in wind environment has occurred through rapid urbanization and growth of high-rise building numbers, This study aims to propose the CFD (Computational Fluid Dynamics) simulation method and evaluation standard of wind environment in site planning of high rise apartment housing. The CFD simulation method proposed in this study is not existing detail simulation, but it is the method that a designer can correct and develop the design through immediate evaluation of design options in concept design phase. Therefore, the proposed CFD simulation method of wind environment in this study uses the BIM based CFD tool in which the 3D model in concept design phase can be used as for the CFD simulation. In this paper, the study examines existing evaluation standards of comfortableness level in wind environment for pedestrian near buildings, and selects new evaluation method which is possible to apply to the proposed CFD simulation method. In addition, it is to examine calculation time-spending and appropriate mesh division method for finding CFD result which is useful to find the best design options in aspect of wind environment in concept design phase. Furthermore, it proposes the wind environment evaluation method through BIM based CFD simulation.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.268-270
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• 2005

A tendency to erect more wind turbines can be observed in order to reduce the environmental consequences of electric power generation. As a result of this, in the near future, wind turbines may start to influence the behavior of electric power systems by interacting with conventional generation and loads. Therefore, wind turbine models that can be integrated into power system simulation software are needed. In this paper, a model that can be used to represent all types of variable speed wind turbines in power system simulations is presented. Wind turbine characteristic equation of a wind turbine is implemented in the RTDS, and the real data of weather conditions are interfaced to the RTDS for the purpose of real time simulation of grid-connection wind power system. The outcomes of the simulation demonstrate the effectiveness of the proposed simulation scheme in this paper. The results show that the cost effective verifying for the efficiency and stability of WPGS.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.3
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• pp.146-152
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• 2004

Cost effective simulation schemes for Wind Power Generation Systems (WPGS) considering wind turbine types, generators and load capacities have been strongly investigated by researchers. As an alternative, a true weather condition based simulation method using a real-time digital simulator (RTDS) is experimented in this paper for the online real-time simulation of the WPGS. A stand-alone WPGS is, especially, simulated using the Simulation method for WPGS using Real Weather conditions (SWRW) in this work. The characteristic equation of a wind turbine is implemented in the RTDS and a RTDS model component that can be used to represent any type of wind turbine in the simulations is also established. The actual data related to weather conditions are interfaced directly to the RTDS for the purpose of online real-time simulation of the stand-alone WPGS. The outcomes of the simulation demonstrate the effectiveness of the proposed simulation scheme. The results also signify that the cost effective verification of efficiency and stability for the WPGS is possible by the proposed real-time simulation method.

• Wind and Structures
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• v.30 no.1
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• pp.69-83
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• 2020

Modelling incompressible, neutrally stratified, barotropic, horizontally homogeneous and steady-state atmospheric boundary layer (ABL) is an important aspect in computational wind engineering (CWE) applications. The ABL flow can be viewed as a balance of the horizontal pressure gradient force, the Coriolis force and the turbulent stress divergence. While much research has focused on the increase of the wind velocity with height, the Ekman layer effects, entailing veering - the change of the wind velocity direction with height, are far less concerned in wind engineering. In this paper, a modified k-ε model is introduced for the ABL simulation considering wind veering. The self-sustainable method is discussed in detail including the precursor simulation, main simulation and near-ground physical quantities adjustment. Comparisons are presented among the simulation results, field measurement values and the wind profiles used in the conventional wind tunnel test. The studies show that the modified k-ε model simulation results are consistent with field measurement values. The self-sustainable method is effective to maintain the ABL physical quantities in an empty domain. The wind profiles used in the conventional wind tunnel test have deficiencies in the prediction of upper-level winds. The studies in this paper support future practical super high-rise buildings design in CWE.

• Journal of the Korean Solar Energy Society
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• v.26 no.4
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• pp.31-38
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• 2006

The national goal of wind energy dissemination has to be determined rationally based on technically available wind resource potential. For an accurate and scientific estimation of wind resource potential, a wind map is requisite. This paper introduces the national wind map of Korea established by numerical wind simulation. Therefore, quantification of national wind resource potential is now possible and is anticipating to be used as a core index for policy and strategy building of wind energy dissemination and technology development.

• Structural Engineering and Mechanics
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• v.75 no.4
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• pp.425-434
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• 2020

Practical non-synoptic fluctuating wind often exhibits nonstationary features and should be modeled as nonstationary random processes. Generally, the coherence function of the fluctuating wind field has time-varying characteristics. Some studies have shown that there is a big difference between the fluctuating wind field of the coherent function model with and without time variability. Therefore, it is of significance to simulate nonstationary fluctuating wind field with time-varying coherent function. However, current studies on the numerical simulation of nonstationary fluctuating wind field with time-varying coherence are very limited, and the proposed approaches are usually based on the traditional spectral representation method with low simulation efficiency. Especially, for the simulation of multi-variable wind field of large span structures such as transmission tower-line, not only the simulation is inefficient but also the matrix decomposition may have singularity problem. In this paper, it is proposed to conduct the numerical simulation of nonstationary fluctuating wind field in one-spatial dimension with time-varying coherence based on the wavenumber-frequency spectrum. The simulated multivariable nonstationary wind field with time-varying coherence is transformed into one-dimensional nonstationary random waves in the simulated spatial domain, and the simulation by wavenumber frequency spectrum is derived. So, the proposed simulation method can avoid the complicated Cholesky decomposition. Then, the proper orthogonal decomposition is employed to decompose the time-space dependent evolutionary power spectral density and the Fourier transform of time-varying coherent function, simultaneously, so that the two-dimensional Fast Fourier transform can be applied to further improve the simulation efficiency. Finally, the proposed method is applied to simulate the longitudinal nonstationary fluctuating wind velocity field along the transmission line to illustrate its performances.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.300-302
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• 2008

For the evaluation of wind resources, numerical simulation was carried out as a tool for establishing wind map around the korean peninsula. Initial and boundary condition are given by 3 hourly RDAPS(Regional Data Assimilation and Prediction System) data of KMA(Korea Meteorology Administration) and high resolution terrain elevation land cover(30 seconds) data from USGS(United States Geological Survey). Furthermore, Data assimilation was adopted to improve initial meteorological data with buoy and QuikSCAT seawinds data. The simulation was performed from 2003 to 2006 year. To understand wind data correctly in complex terrain as the korean peninsula, at this research, Wind map was classified 4 categories by distance from coastline and elevation.

• Wind and Structures
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• v.35 no.6
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• pp.369-383
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• 2022

Wind tunnel experiment was carried out to study the cross-wind layer forces on a square cross-section building model using a synchronous multi-pressure sensing system. The stationarity of measured wind loadings are firstly examined, revealing the non-stationary feature of cross-wind forces. By converting the measured non-stationary wind forces into an energetically equivalent stationary process, the characteristics of local wind forces are studied, such as power spectrum density and spanwise coherence function. Mathematical models to describe properties of cross-wind forces at different layers are thus established. Then, a conditional simulation method, which is able to ex-tend pressure measurements starting from experimentally measured points, is proposed for the cross-wind loading. The method can reproduce the non-stationary cross-wind force by simulating a stationary process and the corresponding time varying amplitudes independently; in this way the non-stationary wind forces can finally be obtained by combining the two parts together. The feasibility and reliability of the proposed method is highlighted by an ex-ample of across wind loading simulation, based on the experimental results analyzed in the first part of the paper.

• Wind and Structures
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• v.31 no.6
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• pp.549-560
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• 2020

Methods for stochastic simulation of non-Gaussian wind pressure have increasingly addressed the efficiency and accuracy contents to offer an accurate description of the extreme value estimation of the long-span and high-rise structures. This paper presents a linear prediction and z-transform (LPZ) based Cumulative distribution function (CDF) mapping algorithm for the simulation of multivariate non-Gaussian fluctuating wind pressure. The new algorithm generates realizations of non-Gaussian with prescribed marginal probability distribution function (PDF) and prescribed spectral density function (PSD). The inverse linear prediction and z-transform function (ILPZ) is deduced. LPZ is improved and applied to non-Gaussian wind pressure simulation for the first time. The new algorithm is demonstrated to be efficient, flexible, and more accurate in comparison with the FFT-based method and Hermite polynomial model method in two examples for transverse softening and longitudinal hardening non-Gaussian wind pressures.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.2
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• pp.980-992
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• 2019

This paper describes a model test and numerical simulation of a 750-kW-semi-submersible platform wind turbine under several wind and wave conditions for validation of the numerical simulation model. The semi-submersible platform was designed to support the 750-kW-wind turbine class and operate at a water depth of 50 m. The model tests were performed to estimate the performance characteristics of the wind turbine system in the wide tank of the University of Ulsan. Motions and loads of the wind turbine system under the wind and wave conditions were measured and analyzed. The NREL-FAST code was used to simulate the wind turbine system, and the results were compared with those of the test model. The results demonstrate that the numerical simulation captures noticeably the fully coupled floating wind turbine dynamic responses. Also, the model shows a good stability and small responses during waves, wind, and operation of the 750-kW-floating offshore wind turbine.