• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 추계학술대회 논문집 학회본부
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• pp.166-169
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• 1990

The purpose of the circuit breaker on power system is to disconnect the faulty part from the system and to maintain the integrity of the system. With switching overvoltages are generated. When the system voltages become higher, switching overvoltage is important factor in insulation co-ordination. Since the no-load reclosing overvoltage with inductive source is severe, this paper deals with the reclosing overvoltage and the effect of closing resistor. This reclosing overvoltage of 27-bus model system with and without closing resistor is analyzed by using EMTP (Electro-Magnetic Transients Program) for both deterministic and Stochastic model.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1234-1235
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• 2011

A DC Power Distribution Systems(DC PDS) are widely used in telecommunication system, electric vehicle, aircraft, military system, etc. In the DC PDS, DC bus voltage instability may be occurred by the operation of multiple loads such as pulsed power load, motor drive system, and constant power loads. To damp the transients of the DC bus voltage, the Voltage Bus Conditioner(VBC) with the PI compensator is used. In this paper, the validity of the proposed VBC system is verified by PSIM simulation package.

• 전기학회논문지P
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• 제56권2호
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• pp.90-98
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• 2007

More and All-Electric Aircraft (AEA) carry many loads with varied functions. In particular, there may be large pulsed loads with short duty ratio, which can affect the normal operation of other loads. In this paper, a bi-directional converter with inductive storage is used as a voltage bus conditioner (VBC) to mitigate voltage transients on the bus. In addition, the constant frequency hysteresis control technique for a VBC is presented. A simple and fast prediction of the hysteresis band-width is implemented by the phase-lock loop control, keeping constant switching frequency. This technique offers the excellent dynamic response in load or parameter variation. The control performance is illustrated by simulated results with the SABER package, The proposed hysteresis control results in the shortest and the smallest excursions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
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• pp.472-475
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• 2008

A DC distributed power system(DPS) has many loads with varied functions. In particular, there may be large pulsed toads with short duty ratio, which can affect the normal operation of other loads. In this paper, a bi-directional converts with inductive storage is used as a DC bus conditioner to damp voltage transients on the bus. In addition, the constant frequency hysteresis control technique for a DC bus conditioner is presented. A simple and fast prediction of the hysteresis band-width is implemented by the phase-lock loop control, keeping constant switching frequency. This technique offers the excellent dynamic response in load or parameter variation. The control performance is illustrated by simulated results with the SABER package. The proposed hysteresis control results in the shortest and the smallest excursions.

• 동력기계공학회지
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• 제19권5호
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• pp.93-98
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• 2015

Nuclear power plants has a number of valves, which are operating at a high temperature-high pressure and radiation environment conditions. Nevertheless, it is important to maintain the reliability of the valves to ensure safe operation of the nuclear power plant. However, the aging of the valves by increasing of years of plant operation and the system transients due to the sudden load change are working the failures of the reliability of the valve. In this paper, we evaluate experimentally the performance change according to the thermal aging of the valve. Results show that the valve stem and the actuator leakages were enlarged by the thermal aging.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.2225_2226
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• 2009

An increasing of non-linear loads such as power electronic equipment in distribution systems is the reason for the greater concern about harmonics in recent time. A harmonic current and voltage in distribution systems can cause many problems such as malfunction of protective equipment. In this paper, Total Harmonic Distortion(THD) of voltage according to magnitudes and measurement locations of the non-linear loads was calculated and analyzed with Electro-Magnetic Transients Program(EMTP).

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.35-37
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• 1993

This paper shows that the presence of constant impedance loads and induction motors in power system's loading contents can lead to transient voltage instabilities during normal system manipulations such as switchings. The abnormal induction motor characteristics during system transients which initiate the voltage instabilities are illustrated. The influence of motor and network parameters, such as motor inertia mechanical load quantity and nature on the severity of the voltage instability are studied.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.253-254
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• 2008

본 논문에서는 계통 부하에 따른 차단기의 최적 개폐시점 선정을 위해 지상 및 진상 부하별 과도회복전압 발생 추이를 분석하였다. 또한 모선 전압의 위상 변화에 따라 차단기의 개극 시점 변화를 통해 발생되는 과도 회복전압의 파형을 분석하여 최적의 개폐 시점 추정을 EMTP(Electro-Magnetic Transients Program) 시뮬레이션 결과로 얻고 부하에 따른 차단기 개폐 제어 방법에 대해 분석하였다.

• 대한전기학회논문지:전력기술부문A
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• 제53권3호
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• pp.161-167
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• 2004

Zone 3 of the distance relay is used to provide the remote back-up protection in case of the failure of the primary protection. However, the risk lot mal-operations under stressed conditions such as heavy loading, voltage and transient instability is usually high. Zone 3 is used in combination with the derivatives of the voltage, and current, etc to prevent mal-operations. Sometimes, the impedance characteristics that restrict the tripping area of relay are used to avoid the mal-operations due to load encroachment. This paper presents a novel Zone 3 scheme based on combining the steady-state components (i.e. 60Hz) and the transient components (TCs) using a state diagram that visualizes the sequence of studies that emanate from the sequence of events. The simulation results show that the novel zone 3 distance relay elements using the proposed method operates correctly for the various events.

• Nuclear Engineering and Technology
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• 제17권2호
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• pp.105-115
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• 1985

정상상태하의 축방향높이 의존적 중성자속 버클링은 3차원적연소 이력자료로부터 도출된다. 과도상태에 있어서는 노내 및 노외중성자 측정기의 반응사이에 존재하는 선형적 관계로부터 물리적인 상관식을 개발하였다. 이 모델을 사용할 경우 제어봉의 위치가 크게 변하는 축방향 출력과도현상을 예측하는 1차원적 중성자 확산이론 프로그램의 신뢰도가 크게 향상된다.