• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1548-1555
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• 2016

This paper presents an application of time series analysis in hourly wind speed simulation and forecast in Jeju Island, Korea. Autoregressive - moving average (ARMA) model, which is well in description of random data characteristics, is used to analyze historical wind speed data (from year of 2010 to 2012). The ARMA model requires stationary variables of data is satisfied by power law transformation and standardization. In this study, the autocorrelation analysis, Bayesian information criterion and general least squares algorithm is implemented to identify and estimate parameters of wind speed model. The ARMA (2,1) models, fitted to the wind speed data, simulate reference year and forecast hourly wind speed in Jeju Island.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.6
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• pp.307-315
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• 2003

This paper proposes a novel simulation method of WPGS (Wind Power Generation System). The rotation speed control method of turbine under variable wind speed using the pitch control is proposed. Moreover, when wind speed exceeds the cut-out wind speed, the turbine will be stopped by controlling pitch angle to 90$^{\circ}$, otherwise it will be controlled to steady-state operation. For the purpose of effective simulation, the SWRW (Simulation method for WPGS using Real Weather condition) is used for the utility interactive WPGS simulation in this paper, in which those of three topics for the WPGS simulation: user-friendly method, applicability to grid-connection and the utilization of the real weather conditions, are satisfied. It is impossible to consider the real weather conditions in the WPGS simulation using the EMTP type of simulators and PSPICE, etc. External parameter of the real weather conditions is necessary to ensure the simulation accuracy. The simulation of the WPGS using the real weather conditions including components modeling of wind turbine system is achieved by introducing the interface method of a non-linear external parameter and FORTRAN using PSCAD/EMTDC in this paper. The simulation of long-term, short-term, over cut-out and under cut-out wind speeds will be peformed by the proposed simulation method effectively. The efficiency of wind power generator, power converter and flow of energy are analyzed by wind speed of the long-term simulation. The generator output and current supplied into utility can be obtained by the short-term simulation. Finally, transient-state of the WPGS can be analyzed by the simulation results of over cut-out and under cut-out wind speeds, respectively.

• KIEE International Transactions on Power Engineering
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• v.3A no.4
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• pp.206-213
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• 2003

The main purpose of this paper is to present a simulation model for assessing the impacts of a variable speed wind turbine (VSWT) on the distribution network and perform a simulation analysis of voltage profiles along the wind turbine installed feeder using the presented model. The modeled wind energy conversion system consists of a fixed pitch wind turbine, a synchronous generator, a rectifier and a voltage source inverter (VSI). Detailed study on the voltage impacts of a variable speed wind turbine is conducted in terms of steady state and dynamic behaviors. Various capacities and different modes of variable speed wind turbines are simulated and investigated. Case studies demonstrate how feeder voltages are influenced by capacity and control modes of wind turbines and changes in wind speed under different network conditions. Modeling and simulation analysis is based on PSCAD/EMTDC a software package.

• Structural Engineering and Mechanics
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• v.45 no.1
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• pp.1-18
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• 2013

The typhoon wind characteristics designing for buildings or bridges located in complex terrain and typhoon prone region normally cannot be achieved by the very often few field measurement data, or by physical simulation in wind tunnel. This study proposes a numerical simulation procedure for predicting directional typhoon design wind speeds and profiles for sites over complex terrain by integrating typhoon wind field model, Monte Carlo simulation technique, CFD simulation and artificial neural networks (ANN). The site of Stonecutters Bridge in Hong Kong is chosen as a case study to examine the feasibility of the proposed numerical simulation procedure. Directional typhoon wind fields on the upstream of complex terrain are first generated by using typhoon wind field model together with Monte Carlo simulation method. Then, ANN for predicting directional typhoon wind field at the site are trained using representative directional typhoon wind fields for upstream and these at the site obtained from CFD simulation. Finally, based on the trained ANN model, thousands of directional typhoon wind fields for the site can be generated, and the directional design wind speeds by using extreme wind speed analysis and the directional averaged mean wind profiles can be produced for the site. The case study demonstrated that the proposed procedure is feasible and applicable, and that the effects of complex terrain on design typhoon wind speeds and wind profiles are significant.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.8
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• pp.935-944
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• 2015

This study performs the dynamic modeling and the simulation of variable speed wind power system and implements the models of wind speed, wind turbine & PMSG, and MPPT & pitch control as well. The simulation of wind turbine was performed by using the power coefficient and other simulation parameters which were extracted with reference to the commercial 5MW class wind turbine data. As the result of this simulation, MPPT control is confirmed, maintaining the maximum power coefficient as far as the rated speed 12[m/s]. Over 12[m/s] wind speed, this wind power system makes it possible to keep the stable output by controlling the pitch angle.

• Architectural research
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• v.18 no.4
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• pp.137-144
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• 2016

The objective of this study was to determine the optimal angle of a wind louver that would induce the optimal wind speed for indoor. Being controlled to have an optimized angle depending on the direction from which wind is blowing and the wind speed, the wind louver to be installed on the building envelop comes to create indoor comfort through a constant wind speed using the function that reduces the indoor wind speed by changing the angle when the wind speed is not lower than a certain level and makes wind flow into the room to the maximum when the wind direction is adverse to catching the wind or the wind speed is not higher than a certain level. To determine the optimal wind louver angle, a core-centered office building with cross-ventilation problems in the climate of Seoul, Korea, which experiences four distinct seasons, was considered for analysis in this study. A module 1 office space model was used for the CFD simulation to analyze the average indoor wind speed with respect to the outdoor wind speed (varied between 1 and 8 m/s), the wind louver angle, and the outdoor wind direction (varied between $0^{\circ}$ and $180^{\circ}$ in steps of $10^{\circ}$).

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.846-848
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• 2000

In the early development of wind energy, the majority of wind turbines were operated at constant speed. Recently, the number of variable-speed wind turbines adopted pitch control apparatus has increased. This paper deal with a simulation of pitch control of variable-speed wind turbine and the response of pitch angle is traced in a given random wind speed.

• KIEE International Transactions on Power Engineering
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• v.4A no.2
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• pp.51-57
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• 2004

This paper describes the dynamic performance of a variable speed wind turbine system responding to a wide variety of wind variations. Modeling of the wind generation using power electronics interface is proposed for dynamic simulation analysis. Component models and equations are addressed and their incorporations into a transient analysis program, PSCAD/EMTDC are provided. A wind model of four components is described, which enables observing dynamic behaviors of the wind turbine resulting from wind variations. Controllable power inverter strategies are intended for capturing the maximum power under variable speed operation and maintaining reactive power generation at a pre-determined level for constant power factor control or voltage regulation control. The components and control schemes are modeled by user-defined functions. Simulation case studies provide variable speed wind generator dynamic performance for changes in wind speed

• Wind and Structures
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• v.26 no.6
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• pp.383-395
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• 2018

An accurate determination of wind speed distribution is the basis for an evaluation of the wind energy potential required to design a wind turbine, so it is important to estimate unknown parameters of wind speed distribution. In this paper, Gumbel distribution is used in modelling wind speed data, and alternative robust estimation methods to estimate its parameters are considered. The methodologies used to obtain the estimators of the parameters are least absolute deviation, weighted least absolute deviation, median/MAD and least median of squares. The performances of the estimators are compared with traditional estimation methods (i.e., maximum likelihood and least squares) according to bias, mean square deviation and total mean square deviation criteria using a Monte-Carlo simulation study for the data with and without outliers. The simulation results show that least median of squares and median/MAD estimators are more efficient than others for data with outliers in many cases. However, median/MAD estimator is not consistent for location parameter of Gumbel distribution in all cases. In real data application, it is firstly demonstrated that Gumbel distribution fits the daily mean wind speed data well and is also better one to model the data than Weibull distribution with respect to the root mean square error and coefficient of determination criteria. Next, the wind data modified by outliers is analysed to show the performance of the proposed estimators by using numerical and graphical methods.

• Wind and Structures
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• v.20 no.2
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• pp.169-189
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• 2015

To investigate the effects of "sudden change" of wind fluctuations on vehicle running performance, which is caused by the artificial discrete simulation of wind field, a three-dimensional vehicle model is set up with multi-body dynamics theory and the vehicle dynamic responses in crosswind conditions are obtained in time domain. Based on Hilbert Huang Transform, the effects of simulation separations on time-frequency characteristics of wind field are discussed. In addition, the probability density distribution of "sudden change" of wind fluctuations is displayed, addressing the effects of simulation separation, mean wind speed and vehicle speed on the "sudden change" of wind fluctuations. The "sudden change" of vehicle dynamic responses, which is due to the discontinuity of wind fluctuations on moving vehicle, is also analyzed. With Principal Component Analysis, the comprehensive evaluation of vehicle running performance in crosswind conditions at different simulation separations of wind field is investigated. The results demonstrate that the artificial discrete simulation of wind field often causes "sudden change" in the wind fluctuations and the corresponding vehicle dynamic responses are noticeably affected. It provides a theoretical foundation for the choice of a suitable simulation separation of wind field in engineering application.