• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.5
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• pp.873-878
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• 2009

When the transmission lines are initially energized for power system restoration, the power system suffers the various overvoltages that can be classified as steady-state, transient, and dynamic overvoltages. For the accurate analyses of these overvoltages, many researchers utilize different simulation tools such as Power System Simulator for Engineering(PSS/E). Although PSS/E provides good solutions in steady-state and dynamic overvoltages, it is not suitable for transient overvoltages. Therefore, transient overvoltages are simulated by using Electro-Magnetic Transients Program(EMTP) developed for the analysis of transients in the power system. Recently, EMTP can be also used to simulate dynamic behavior of the system. In order to analyze the transient overvoltages with steady-state and dynamic overvoltages, the authors adopt EMTP as the simulation tool for the analysis of overvoltages. This paper presents the simulation results for the analyses of various overvoltages, and the possibility of EMTP to be used for these types of analyses.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1445-1450
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• 2007

Induction motors are the main driving force of electric vehicles and operated by pulse width modulation (PWM) inverters in speed control. Contrary to full-voltage operation of induction motors, inverter-fed induction motors (IFM) generates transient overvoltages up to 10 kV/us and transient overvoltages accelerate the deterioration of winding insulation. We investigated transient overvoltages produced by the operation of IFM and analyzed its peak value and dv/dt depending on power cable length and operation frequency. The experimental results showed that transient overvoltages measured at the motor terminal increased with the cable length between inverter and motor.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.33 no.3
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• pp.118-124
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• 1984

This paper investigated the characteristics of transient overvoltages on the tower caused by time varying tower footing resistance in the path of lightning stroke current entering earth on transmission lines. The tower with time varying tower footing resistance was simulated and the transient overvoltageson the tower due to lightning stroke current were computer by Nodal Solution Method. From the results, it was found that the determination of the steady state values as a limit of inductive tower footing resistance causes higher transient overvoltages than CFO voltages of insulator strings and V-T characteristics of the insulator strings should be considered for computation of backflashover rate.

• KIEE International Transactions on Power Engineering
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• v.5A no.4
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• pp.366-370
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• 2005

To meet increasing power demand, 500 kV power systems are under consideration in the regions of some Middle Asian countries. As the power system voltage becomes higher, the cost for the power system insulation increases significantly. 500 kV transmission systems will become the basis of a region's power system and they require much higher system reliability. Consequently, by the methods of limiting overvoltages effectively, a reasonable insulation design and coordination must be accomplished. In particular, the Substations must be constructed to be of outdoor type. In order to determine the various factors for the insulation design, the EMTP (Electro-magnetic transient program) is used for the magnification of transient phenomena of the 500 kV systems in the planned network. In this paper, we will explain the calculation results of lightning overvoltages by the EMTP for lightning protection design for the 500 kV substations. To obtain reliable results, the multi-story tower model and EMTP/TACS model are introduced for the simulation of dynamic arc characteristics.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1622-1624
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• 1994

Among the power system overvoltages, switching overvoltages are analysed in this paper, using EMTP(Electro-Magenetic Transient Program ) and TNA(Transient Network Analyzer ). From this analysis, the switching overvoltages are used to determine the BSL(Basic Switching Withstand Level) and the clearance of the transmission tower. Up to now the switching overvoltages were analysed by EMTP, but in order to determine the more exact value of BSL, not only digital but also analog method is required.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.232-234
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• 2002

A Vacuum Circuit Breaker Model for simulation of transient overvoltages was developed by using the PSCAD/EMTDC. The Model includes the power frequency chopping current. Breaker withstand voltage, and quenching capability of High frequency currents. To verify the abilities of the breaker model, the simulation on the Lindmayer's single-phase circuit was carried out. The results show that using the proposed model, the transient overvoltages, current chopping, and multiple reignitions of vacuum breaker are properly reproduced as real phenomena. In further study, virtual chopping current will be incorporated into the model for 3 phase system.

• Journal of Electrical Engineering and Technology
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• v.7 no.3
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• pp.297-303
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• 2012

This paper presents the simulation results for the analysis of a lightning surge, switching transients and very fast transients within a thermal plant. The modeling of gas insulated substations (GIS) makes use of electrical equivalent circuits that are composed of lumped elements and distributed parameter lines. The system model also includes some generators, transformers, and low voltage circuits such as 24V DC rectifiers and control circuits. This paper shows the simulation results, via EMTP (Electro-Magnetic Transients Program), for three overvoltage types, such as transient overvoltages, switching transients, very fast transients and a lightning surge.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.5
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• pp.51-59
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• 2003

The utility and many customers employ capacitor banks(STATCON so called at the utility) to help control the power factor(customers) or voltage(the utility) by supplying reactive power to inductive loads. This paper presents analysis of transient overvoltages and harmonics due to utility STATCON switching. One simple and inexpensive means of limiting the voltage magnification transient and reducing harmonics is to switch the capacitor banks on a few minutes after the STATCON has been switched. Simulation results used the EDSA software package show the effects of decreased the transient voltage and harmonic reduction at the customer. And also harmonic limits based on the well-known international harmonic standards IEEE 519 and IEC 1000 are evaluated for the customer.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.1161-1165
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• 2005

Due to the miniaturization of electrical components and assembles on signal circuits, transient overvoltages caused by switching operation or lightning surges have become more interesting concern to the field of electrical engineering. In this paper, the development of surge protective devices(SPDs) that can protect sensitive signal device on shipboard from overvoltages are described. Two kinds of SPDs are designed and tested by using a combination surge generator which can produce the standard impulse current of 8/20${\mu}s$ 2.1kA according to the IEC 61000-4-5 standard. From the simulation and experimental results, it is confirmed that the proposed SPDs have an enough protection performance with a low insertion loss and a low clamping voltage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.480-483
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• 1997

This paper describes dielectric characteristics and discharge development mechanisms of SF$_{6}$ gas stressed by very fast transient overvoltages in inhomogeneous electric field. Predischarge phenomena of SF$_{6}$ gas in non-uniform fields are statistically investigated with positive and negative very fast trannsient overvoltages. It was confirmed that all of the predischarges of the positive and negative polarities develop in a regime of stepwise leader extension. i.e, the predischarge developments leading to breakdown against very fast transient overvoltages are similar to the non-oscillating impulse voltages.ges.