• 전자공학회논문지 IE
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• v.43 no.1
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• pp.32-38
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• 2006

When induction motor moves, power quality decline of line is risen seriously because provoking voltage drop the moment to system power supply by excessive moving current as well as power-factor drop in case drive by light-load because current reaches in 6 times $\sim$ 8 times of rated current. In this paper, a modeling did an distribution system 13 bus type model and induction machine load presents in IEEE using a PSCAD/EMTDE package, and it displayed an accident conspiracy and a compensating factor of DSTATCOM through simulation show.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.1
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• pp.56-60
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• 2005

In the power-line communication(PLC) systems, the power line is a wired medium. However, the power line channel has the multi-path fading characteristics like the wireless channel in the wireless communication systems because it has the signal reflection and divergence by the impedance mismatching between many branch lines and loads. So the analysis of the multi-path characteristics is very important, and it has been doing by the several measurement methods for the impulse response between the transmitter and the receiver. PN sequence method has originally been used as a wideband impulse response measurement mettled for wireless channel, but it is recently being applied to not only the wireless channel but also the wired channel like the power line channel. This method is more useful and effective for the long distance communication channel like the medium voltage power distribution line with the multi-paths[1]. In this thesis, we have measured impulse response for the medium voltage power distribution line channel by the wideband measurement method using PN sequence, analytically studied the measured data and presented the results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.12
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• pp.2135-2142
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• 2010

This paper studies the validity about a joint operation of neutral wire and overhead grounding wire in combined distribution systems. The overhead grounding wire and neutral wire are currently installed separately and grounded by common. However there is no any ineffectiveness or electrical problem in case of the proposed system, such system can be operated at real distribution system. Therefore this paper describes the suitability of a joint operation through lightning surge analysis on combined distribution systems. Lightning surge analysis is carried out by EMTP/ATPDraw to obtain the overvoltage of overhead line and underground cable in various conditions such as locations and current types of lightning stroke. Overvoltage gained by the analysis show that the insulation strength of the joint operation case is not stable compare with the current operation case.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.10
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• pp.1376-1382
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• 2013

This paper analyzes the propagation characteristics of lightning surge according to the type of branch line in distribution system. The types of branch line considered are H-type and PI-type. At each type, the length of main feeder is same, while the number and length of branch line are different. The distribution line is modeled and the various lightning locations are simulated by Electromagnetic Transient Program(EMTP). For each lightning, the various measuring points are selected. Based on the simulation results, the propagation characteristics of lightning surge at each measuring point are analyzed. The analyzed results are verified by travelling wave theory.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2154-2155
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• 2011

국내의 전력계통은 송전거리가 짧고, 전력공급의 신뢰도 및 안정도 향상을 위해서 망상구조로 되어있다. 이러한 구조는 사고시 임피던스 저하로 인해 사고전류의 크기가 차단기 차단내력을 초과하게 된다. 또한 전력수요 증가로 인해 사고전류의 크기는 계속 증가하고 있다. 이러한 문제점을 해결하기 위해서 배전계통의 장비 및 대용량 보호 기기로의 교체나 모선 분리 등의 방법을 실시하고 있지만 평사시 계통에 미치는 영향과 손실 발생에 따른 효율저하, 대용량 차단기로의 교체에 따른 경제적인 문제를 수반하게 된다. 이러한 문제점을 효과적으로 해결하기 위해 초전도 한류기가 고안되었다. 본 연구에서는 변압기와 초전도 소자를 이용한 자속 결합형 초전도 한류기의 3상 사고전류제한 실험을 수행하였다. 자속 결합형 초전도 한류기는 평상시 정상 상태에서는 초전도 소자가 저항을 발생시키지 않고, 1, 2차 리액터에서 발생하는 자속은 서로 상쇄되어 전압이 유기되지 않음으로써 아무런 손실 없이 동작한다. 하지만 계통에서 사고가 발생하여 초전도 소자 임계 전류값 이상의 사고전류가 유입되면 초전도 소자가 ��치되어 저항을 발생하게 된다. 또한 병렬로 연결된 2차측 리액터에 사고 전류가 bypass되어 1, 2차 리액터에서 전압이 유기되고 이에 따라 안정적으로 사고전류를 제한하게 된다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.535-536
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• 2011

This paper studies the validity about a joint operation of neutral wire and overhead grounding wire in combined distribution systems. The overhead grounding wire and neutral wire are currently installed separately and grounded by common. However there is no any ineffectiveness or electrical problem in case of the proposed system, such system can be operated at real distribution system. Therefore this paper describes the suitability of a joint operation through lightning surge analysis on combined distribution systems and analyzes the optimal position of lightning arrester on joint operation of neutral wire and overhead grounding wire. Lightning surge analysis is carried out by EMTP/ATPDraw to obtain the overvoltage of overhead line and underground cable in various conditions such as location and current types of lightning stroke. Over voltage gained by the analysis show that the insulation strength of the joint operation case is not stable compare with the current operation case.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2140_2141
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• 2009

We used the eddy current sensor for a 22.9kV distribution power line insulation cable diagnosis. The insulation cable which is used in the 22.9kV distribution power line is having element wire from 6 to 18. Consequently, currently to ECT applications it has a limit in the distribution power line. We about under producing to apply in pick-up coil forms and the differential total coil form where becomes sum of zero in order to have. From measurement result, partial broken cable was confirmed 500 mV~980 mV changes from normal state.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.2
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• pp.224-229
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• 2014

This paper presents the novel voltage control method in power distribution system with distributed generators. The voltage in distribution systems is regulated by Under Load Tap Changer(ULTC) of substation and pole transformer of primary feeders. Recently, Step Voltage Regulator(SVR) is getting located at distribution feeders to regulate effectively voltage of primary feeders. But the effectiveness of SVR decreases due to independent operation between SVR and ULTC, and also the existing Line Drop Compensator(LDC) method considering the distributed generators may be not able to regulate the proper voltage in a permissible range. Thus, this paper presents a optimal voltage control algorithm of SVR by using the secondary voltage data of main transformer in substation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.7
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• pp.37-44
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• 2013

Phase to ground faults are possibly one of the maximum number of faults in power distribution system. During a ground fault the maximum fault current and neutral to ground voltage will appear at the pole nearest to the fault. Distribution lines are consisted of three phase conductors, an overhead ground wire and a multigrounded neutral line. In this paper phase to neutral faults were staged at the specified concrete pole along the distribution line and measured the ground fault current distribution in the ground fault current, three poles nearest to the fault point, overhead ground wire and neutral line. A simplified equivalent circuit model for the distribution system under case study calculated by using MATLAB gives results very close to the ground fault current distribution yielded by field tests.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.603-605
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• 2005

전력수요의 증대에 따른 계동모의 확장에 따라 관련기기는 초고압 및 대용량화 추세에 있다. 이러한 관련기기들 중에서도 특히 154/22.9kV 전력용 변압기는 고장시 수용가의 정전범위가 방대하고 변압기 내부 고장의 복구비용 또한 막대하므로 경제적 손실은 물론 사회적 영향도 크다. 우리나라에서는 1980년 초기부터 154/22.9kV 전력용 변압기의 고장이 급증하였으며, 이러한 원인은 주로 직전접지 방식을 채택하고 있는 한전 계통에서 배전선의 지락고장에 의한 지락고장 전류가 변압기 중성점을 통하여 변압기에 충격을 가함으로써 변압기 권선 단락 절연파괴 및 ULTC 고장 등이 발생하는 것으로 밝혀졌다. 따라서 한전에서는 변압기 중성점으로 흐르는 지락고장전류의 저감을 위해 변압기 중성점 접지 리액터(NGR: Neutral Ground Reactor)를 설치하여 운전하고 있으며, 결과 변압기 고장이 크게 감소하였다. 그러나 모선 절체시 변압기 1, 2차측 차단기 Trip 고장이 발생하였으며, 고장 발생 원인은 NGR 보호계전기 59GT 계전기의 오동작에 의한 86T Lock Out 계전기 동자으로 변압기 1, 2차측 차단기 Trip 고장이 발생한 것으로 추정된다. 따라서 본 논문에서는 무부하 모선 차단시 59GT 계전기에 나타나는 이상 전압을 EMTP (electro-magnetic transient program)를 이용하여 분석하였다.