• 전기학회논문지
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• 제58권5호
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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.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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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.

• 대한전기학회논문지
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• 제33권3호
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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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• 제5A권4호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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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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• 제7권3호
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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.

• 조명전기설비학회논문지
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• 제17권5호
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• pp.51-59
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• 2003

전력회사와 수용가들은 유도성 부하에 무효전력을 공급하여 역률(수용가)이나 전압(전력회사)을 조절하기 위해 커패시터 뱅크(전력회사는 스타콘이라 함)를 설치 운영하고 있다. 본 논문에서는 전력회사의 스타콘 투입시 발생되는 과도 전압 상승과 고조파를 분석하고자 한다. 과도 전압과 고조파를 저감시키는 간단한 수단중의 하나는 수용가의 커패시터 뱅크를 전력회사의 스타콘을 투입한 후에 과도상태가 지난뒤에 투입하는 방법이다. EDSA프로그램으로 컴퓨터 시뮬레이션을 수행하여 수용가에서의 과도 전압 상승과 고조파 저감 효과를 검증 하였다. 그리고 수용가에서 발생하는 고조파를 잘 알려진 국제 고조파 관리 기준인 IEEE 519와 IEC 1000으로 비교해 보았다.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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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.