• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.11
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• pp.1971-1979
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• 2010

As a result of increasing environmental concern, the penetration of renewable power on power systems is now increasing. Wind energy can be considered as the most economical energy sources to generate electricity without depletion of fossil fuel. To devise adequate control strategies for wind farm, time domain simulation analysis needs to be performed. This presents a continuation time integration (CTI)-based time domain simulation algorithm for wind farm with doubly fed asynchronous generator (DFAG) connected to the external power systems. This paper depicts how to time trajectories are traced using CTI-based time domain simulation. Also this paper describes the possibilities of hierachical control for wind farm output limitation, and the coordinated control has been designed by hierarchical control structured from central control level to wind farm control board and to an individual wind turbine level. Finally it shows an illustrative example of time domain simulation result with two test systems through case study.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.10
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• pp.21-25
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• 2010

This paper explains hybrid method that combines Time domain simulation technique with the direct method of Transient stability analysis. First, it calculate trajectory of real system by Time domain Simulation using OOP(Object Oriented Programming method) and evaluate Transient Energy Function to induce stability index to calculate Transient stability margin. Once the status of system(stable or unstable) has been identified, proper criteria are proposed to stop time-domain simulation to reduce CPU time.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.439-442
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• 2009

As a result of increasing environmental concern, the penetration of renewable power on power systems is now increasing. Wind energy can be considered as the most economical energy sources to generate electricity without depletion of fossil fuel. The penetration of wind energy from wind farm is getting larger and larger, so we need adequate control strategies for wind farm. To devise adequate control strategies for wind farm, time domain simulation analysis needs to be performed. This presents a Simultaneous Implicit-based time domain simulation algorithm for wind farm with DFAG (Doubly Fed Asynchronous generator) connected to the external power systems. This paper shows an illustrative example with a 5-bus test system.

• Smart Structures and Systems
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• v.14 no.6
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• pp.1197-1220
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• 2014

Accurate actuator tracking is critical to achieve reliable real-time hybrid simulation results for earthquake engineering research. The frequency-domain evaluation approach provides an innovative way for more quantitative post-simulation evaluation of actuator tracking errors compared with existing time domain based techniques. Utilizing the Fast Fourier Transform the approach analyzes the actuator error in terms of amplitude and phrase errors. Existing application of the approach requires using the complete length of the experimental data. To improve the computational efficiency, two techniques including data decimation and frequency decimation are analyzed to reduce the amount of data involved in the frequency-domain evaluation. The presented study aims to enhance the computational efficiency of the approach in order to utilize it for future on-line actuator tracking evaluation. Both computational simulation and laboratory experimental results are analyzed and recommendations on the two decimation factors are provided based on the findings from this study.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.446-448
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• 2007

This paper presents the high frequency (HF) eigenvalue results against IEEE SSR First Benchmark Mode and validation using the simultaneous time-domain simulation program, PSCAD/EMTDC. Two results show a little difference but not much. Particularly, HF eigenvalue analysis results tends to give more conservative results compared to those of the exact time-domain simulation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.658-664
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• 2012

This paper presents an investigation into driveline clonk noise of midi-bus. Test was performed for operational acceleration and pressure, torsional vibration of driveline and FRF to TPA. Wavelet analysis was used to study spectral-time characteristics to all measurement data and specially for torsional vibration, lash analysis was carried out. To investigate the path of the clonk in detail, time domain TPA was introduced. With time domain TPA, the contribution of each path for the clonk was estimated by both subjectively and objectively. As a result, Transmission mount part was came to light as the main contributor of issued clonk. This was verified by reinforcing the bracket of transmission side. And 1D torsional nvh performance simulation model was built with measured torsional vibration. The simulation tool was used for prediction of some clonk behavior in tip in-out transient condition.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.480_481
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• 2009

As a result of increasing environmental concern, the penetration of renewable power on power systems is now increasing. Wind energy can be considered as the most economical energy sources to generate electricity without depletion of fossil fuel. To devise adequate control strategies for wind farms, time domain simulation analysis needs to be performed. This paper presents a time domain simulation method for wind farms with fixed speed wind turbines (FSWT) connected to the external power systems. In this paper, an example of time simulation of the wind farm with four FSWT.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.2
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• pp.111-117
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• 2008

This paper presents a new continuation-based quasi-steady-state(CQSS) time-domain simulation algorithm incorporating a multiplicative aggregated load model for power systems. The authors' previous paper introduced a CQSS algorithm, which has the robust convergent characteristic near the singularity point due to the application of a continuation method. The previous CQSS algorithm implemented the load restoration in power systems using the exponent-based load recovery model that is derived from the additive dynamic load model. However, the reformulated exponent-based model causes the inappropriate variation of short-term load characteristics when switching actions occur, during time-domain simulation. This paper depicts how to incorporate a multiplicative load restoration model, which does not have the problem of deforming short-term load characteristics, into the time simulation algorithm, and shows an illustrative example with a 39-bus test system.

• Journal of Drive and Control
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• v.15 no.4
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• pp.67-73
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• 2018

The paper deals with an approach to time domain simulation for closed end at the downstream of pipe, hydraulic lines terminating into a tank and series lines with change of cross sectional area. Time domain simulation of a fluid power systems containing hydraulic lines is very complex and difficult if the transfer functions consist of hyperbolic Bessel functions which is the case for the distributed parameter dissipative model. In this paper, the magnitudes and phases of the complex transfer functions of hydraulic lines are calculated, and the MATLAB Toolbox is used to formulate a rational polynomial approximation for these transfer functions in the frequency domain. The approximated transfer functions are accurate over a designated frequency range, and used to analyze the time domain response. This approach is usefully to simulate fluid power systems with hydraulic lines without to approximate the frequency dependent viscous friction.

• Journal of the Optical Society of Korea
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• v.18 no.6
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• pp.766-771
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• 2014

Single-ring all-pass filters with various coupling ratios are designed, fabricated, and characterized to assess the validity of the split-step time-domain modeling approach, which is considered for direct simulation of time-domain characteristics, such as optical delay, of various ring resonator devices. When the coupling ratio of the single-ring all-pass filter is 0.4 and 0.8, the delay time is measured to be about 145 and 42 ps respectively, which is comparable to the time-domain modeling results of 151 and 47 ps respectively. The measurements for two- and three-ring all-pass filters are also found to agree quite well with the simulation results. With these results it is confirmed that the split-step time-domain model could be efficiently incorporated into an optical-communication simulation module for ring resonator delay components in an all-optical packet switching system.