• 전기학회논문지
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• 제61권7호
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• pp.937-943
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• 2012

Most of faults occurred in transmission lines are single-phase to ground faults and transient faults. Single-phase auto reclosing is an appropriate scheme to maintain the system stability and restore the system effectively when those faults are occurred. In single-phase auto reclosing scheme, the secondary arc is generated after faulted phase is tripped to eliminate the fault and it is sustained by the capacitive and inductive coupling to the healthy phases. It is important to reclose the faulted phase after fully extinction of secondary arc because of the damage applied to system. Therefore, it is necessary to research on the detection of secondary arc extinction to ensure high success rate of reclosing. In this step, firstly, the accurate modelling of secondary arc should be performed. In this paper, the modelling of secondary arc is performed by using EMTP-RV and the simulation results show that the implemented model is correct and effective.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.458-460
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• 2001

This paper described the unbalanced voltage on the tertiary bus of a single Phase auto transformer in the case of parallel operation with different manufacturer at each Phase. The unbalanced capacitances between primary to secondary winding, secondary to tertiary winding and primary to tertiary winding makes unbalanced bus voltage in the tertiary bus side. The unbalanced voltage let the surge arrester to operate in the power frequency range, and it causes the arrester to burn out. The failure of the arrester at one phase makes line to ground fault, which lead to the surge arrester failure of the other two phase on the tertiary bus.

• Journal of Advanced Marine Engineering and Technology
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• 제33권8호
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• pp.1232-1238
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• 2009

전력설비의 대용량, 고전압화 됨에 따라 발전기 고장 예방을 위한 고장보호시스템의 필요성이 점차 증대되고 있다. 신속하고 신뢰성 있게 운전하며 보호하는 발전기 보호제어 시스템의 개발이 시급히 요구된다. 본 논문에서는 전력 공급의 안정을 도모하고 대용량, 고전압화 되는 발전기의 고장 예방을 위한 발전기 보호기능을 갖춘 디지털 보호계전기 설계에 관한 연구를 수행하였다. 디지털 계전기의 발전기 고장보호에 사용되는 고장보호 알고리즘을 개발하였고 디지털보호계전기 H/W를 설계 제작하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.1044-1047
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• 1999

This paper deals with the dynamic property of ground overvoltage relay in large turbine generator. Relay operation is based on detecting the fundamental voltages originating from the generator. Calculations of fault voltage and current are reviewed for the neutral ground resistance. The frequency, ampitude and waveform of individual harmonics were measured using power quality analyzer and memory hi-corder at the secondary side of ground potential transformer. The ac and dc high-potential tests were applied to evaluate the condition of generator, main and auxiliary transformer, isolated phase bus, potential transformer, surge capacitor and arrester.

• 한국지능시스템학회논문지
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• 제17권3호
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• pp.374-379
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• 2007

본 논문은 전력계통의 배전계통시스템에서 FRTU(Feeder remote terminal unit)의 고장검출 알고리즘의 개선에 관한 연구이다. FRTU는 상과 지락에 관한 고장검출을 할 수 있다. 특히 고장픽업 기능과 돌입억제기능은 일반적인 부하전류로부터 고장전류를 구별할 수 있다. FRTU는 돌입전류 또는 설정값을 초과한 고장전류가 발생하면 고장표시기(FI)로 고장을 발생한다. 짧은 시간 푸리에 변환(STFT) 분석은 주파수와 시간에 관한 정보론 제공하고, 퍼지 중심 평균 클러스터링(FCM) 알고리즘은 고조파의 특성을 추출한다. 고장 검출기의 신경회로망 시스템은 최급강하법을 이용하여 고장상태로부터 돌입전류를 구별하도록 학습된다. 본 논문에서는 FCM과 신경회로망을 이용하여 고장검출기법을 개선하였다. 검증에 사용된 데이터는 22.9KV 배전계통 시스템에서 실제 측정된 데이터이다.

• 한국지진공학회논문집
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• 제15권5호
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• pp.25-33
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• 2011

비선형 시간이력응답해석에서 입력지진동은 구조물의 탄소성 지진응답을 결정짓는 중요한 요소이다. 시간이력해석에 사용되는 기록지진동파형은 지진발생 메카니즘, 전달경로, 지반의 성질에 따른 여러 가지 인자가 복잡하게 관련되어 있기 때문에 구조물의 지진응답해석에 사용될 일반성을 갖는 입력지진동을 선정하는 것은 매우 어려운 문제이다. 본 논문은 실무에서 내진설계용 지진동으로 가장 선호하지 않는 입력지진동을 선정하여 인공지진동파형을 작성하였다. 인공지진동은 기록지진동과 동일한 위상각을 가지며, 감쇠정수 h=5%일 때의 설계용 스펙트럼과 거의 일치하도록 작성되었다. 기록지지동과 인공지진동을 입력한 1자유도계의 탄성 및 탄소성 지진 응답해석을 수행하여 탄소성 응답스펙트럼 및 입력에너지 응답 특성을 분석하였다. 본 연구에서 작성된 인공지진동은 건축구조물의 탄소성 지진응답해석용 입력지진동으로 충분히 타당성이 있다고 사료된다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.43.1-43.1
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• 2011

The detail simulation modeling of fully-fed induction generator is investigated through PC based MATLAB/Simulink environment. Generator's stator currents are controlled by indirect vector control method. In this method, generator side converter controls the maximum excitation (air gap flux) by stator d-axis current and controls generator torque by stator q-axis current. Induction generator speed is controlled by tip speed ratio (TSR) upon the wind speed variations in order to generate the maximum output power. The generator torque model is specified as a 3-blade wind turbine with rating, then, the model is simulated under normal operating condition and three different fault conditions. The matlab model designed for fully-fed induction generator based wind farm provides good performance under normal and grid fault conditions. It provides good results for different pwm techniques and fault conditions except the single-phase line to ground fault, which should be verified with real time data from wind farms.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1659-1662
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• 1998

This paper is to analyze electromagnetic fields on a 154kV substation system and induced voltages on the substation fence when the network is operating in a normal condition or a fault condition in which one phase is shorted with the overhead ground wire. Also, changing the scalar potential and electromagnetic fields that are changed in accordance with changing resistivity and permeability of ground are studied. A finding of the study is that the scalar potential and electromagnetic fields are raised near the tower: The values of electric field on the corner of fence and at the edge of the ground grid are higher than other locations.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
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• pp.284-287
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• 2006

In this paper variety test results were discussed regarding to the ground potential increase. The tests conducted with a joint box simulating leakage point having an insulator fault. Inside the joint box three-phase cables and one neutral line were connected and the insulator at jointed part was peeled from the one of three-phase cables. The potentials around manhole cover were measured with the variation of manhole material, ground resistance and water resistance when the manhole was flooded. The potentials induced by an electric leakage were drastically decreased with increasing the distance from the leakage location and with less ground resistance.

• 전기학회논문지
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• 제62권11호
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• pp.1604-1609
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• 2013

When the ground fault on the power side occurs on distribution system interconnected with distributed generations, the abnormal current is generated in the neutral conductor by the connection type and the iron core structure of transformers for the interconnection of distributed power supplies due to the unbalanced voltage of the system, and subsequently the false operation of the protective relay on the load side occurs. Herein, this paper proposes the method to correct errors in the phase current to prevent the false operation of the protective relay by applying p-q theory and presents the simulation result of the error correction algorithm using PSCAD/EMTDC.