• 대한전기학회논문지:전력기술부문A
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• 제50권8호
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• pp.359-364
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• 2001

This paper presents the influence of the lightning overvoltage and the shielding effect of lightning arresters and overhead grounding wires on the DC railroad systems. Modeling of railroad system is established in ATPDraw to perform the simulation and the line constants of railroad were calculated using ATP_LCC. When a direct lightning strikes to the DC railroad, the result of simulation reveals that the shielding effect of arresters is reduced at messenger, trolly-wire, and the shielding effects of overhead grounding wire is over 90% than the case which does not include it. Therefore it is evaluated that overhead grounding wires should be installed in the DC railroad line.

• 대한조선학회논문집
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• 제32권4호
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• pp.73-86
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• 1995

본 연구에서는 선박의 전진형 좌초(grounding with a forward speed)에 대한 손상 메카니즘을 분석하고, 구조손상 추정모델을 제안하였다. 손상 추정모델의 정도와 적용성을 검증하기 위하여 다양한 실험결과들과 비교하였다. 또한, 좌초사고에 의해 선저부가 손상을 입었을 경우 잔류강도(residual strength)의 부족으로 인한 선각의 점진 붕괴해석을 ALPS/ISUM 컴퓨터 코드를 이용하여 수행하는 방법을 제시하였다. 이 방법을 AFRAMAX급 Transverseless 이중선체 유조선의 좌초 해석문제에 적용하고, 구조손상의 크기와 붕괴 가능성을 검토하였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권8호
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• pp.347-353
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• 2002

This paper presents an accurate method for measuring the ground resistance in powered grounding system. Most of substations and electric power equipments are interconnected to an extensive grounding network of overhead ground wires, neutral conductors of transmission lines, cable shields, and etc. The parasitic effects due to circulating ground currents and ground potential rise make a significant error in measuring the ground resistance. The test current transition method was proposed to reduce the effects of stray ground currents, ground potential rise and harmonic components in measurements of the ground resistance for powered grounding systems. The instrumental error of the test current transition method is decreased as the ratio of the test current signal to noise(S/N) increases. It was found from the test results that the proposed measuring method of the ground resistance is more accurate than the conventional fall-of-potential method or low-pass filter method, and the measuring error was less than 3[%]when S/N is 10.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 춘계학술대회 논문집 전기설비전문위원
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• pp.51-53
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• 2005

Grounding systems are responsible rot the safe operation of a power system whetehr power system fault occures or not, their performance guarantees equipmet protection and personnel safety by limited the ground potential rise and touch voltages as well as step voltages under ground fault condition. therefore, it is necessary to measure the ground resistance frequently for checing the performance of grounding system. In order to verigy the designed grounding measurement system feasibility, two comparison verifications, which are the ground resistnace measurements using the designed system on power service and off power service, are carried out for the same substation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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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.

• 한국산학기술학회논문지
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• 제15권4호
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• pp.2343-2348
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• 2014

지락사고 시 지락전류에 의한 전위경도 상승으로부터 인체를 보호하기 위하여 발전소의 주 접지망을 구성한다. 이를 위한 접지설계시 일반적으로 IEEE Std-80-2000(한전설계기준 2602)에 의하여 계산한다. 그러나 이는 수상환경에서 적용하기 힘들어 수상태양광의 접지저항 확보를 위한 접지기술이 명확하지 않다. 그런데 500kW 수상태양광의 모듈표면 및 금속덕트에 정전기가 발생하고 있고, 안정적인 접지확보를 위해서는 수상환경의 접지방식에 대한 구체적인 방안이 필요한 실정이다. 따라서 본 논문에서는 수상환경에서 Wenner 4 전극법으로 대지저항률을 조사.분석하였으며, 현재 운영중인 수상태양광의 접지저항을 국제규격(IEEE std-81)에서 제시하는 전압강하법으로 측정 분석하여 안정적인 접지확보를 위한 수상태양광 접지방안을 제시하였다. 수면 1m 수중의 저항률이 ($126.3969[{\Omega}{\cdot}m]$) 하상의 저항률($97.5713[{\Omega}{\cdot}m]$)보다 대체로 높은 것을 측정 분석되었고, 제시한 접지앵커 접지방안은 수상태양광의 더욱 안정된 접지저항 확보를 위해 경제적으로 가장 효과적인 방법으로 판단되며, 향후 수상태양광 발전의 접지방법으로 활용될 것으로 기대된다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 학술대회 논문집
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• pp.293-295
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• 2004

Public utilities adopt the grounding rules ; class I, class II, class III and special class III, and install the grounding electrodes in distribution facilities. To keep the safety of the human and the facilities, Public utilities also manage the value of ground resistance in distribution system biennially. At present the Hook-On meter is normally used to measure the ground resistance although it has ${\pm}5[%]$ measuring error and it can not measure the exact value when the current is over 1[A]. In addition it is very difficult to use the fall-of-potential method in distribution system. In this paper we propose the new measurement method using ground current of distribution system as the current source.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2000년도 학술대회논문집
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• pp.77-81
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• 2000

The purpose of this paper is to describe a new measuring method of ground resistance for the grounding system in energized power equipment and substations. It is very difficult to measure the accurate ground resistance in energized power equipment and substations because of the noise conducted from all external connections to the grounding system and harmonics components caused by unbalanced loads and overloads. The ground resistance that is measured with existing methods includes not only the effect of desired signals but also noise components for the measurement period in grounding system. The measured value of ground resistance can entirely be different from actual value. In this paper, to eliminate 60[Hz] power system interference and harmonic components the low-pass filter method was used in the measurement of ground resistance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 A
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• pp.79-81
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• 2000

Measurement used electrical sounding(MacOHM 2115, Japan) for large scale grounding resistance of So-Yang Dam hydroelectric power plant. To applied measurement method is fall of potential method. This result propose to method of efficient administration for grounding system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.740-741
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• 2007

This paper analyses the transient state of underground distribution system against single line to ground fault in underground transmission systems, when underground transmission systems and distribution systems are made of common grounding. Underground transmission systems and distribution systems are modeled by EMTP/ATPDraw. Simulation is carried out considering variation of parameters such as value of common grounding, balance load and unbalance load.