• 대한전기학회논문지:전력기술부문A
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• 제48권1호
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• pp.16-21
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• 1999

The analysis of distribution line faults is essential to the proper protections of the power system. A high impedance fault test, which was carried in Korean electric power systems, it was found that a arcing phenomenon occurred during the high level portion of conductor voltage in each cycle. In this paper, we propose a new method for detection of high impedance faults, which uses the arcing fault current difference during high voltage and low voltage portion of conductor voltage waveform. To extract this difference, we diveded one cycle fault current into equal spanned four data windows according to the magnitude of voltage waveform and applied fast fourier transform(FFT) to each data window. The frequency spectrum of current wavefrom in each portion are used as the inputs of neural network and is trained to detect high impedance faults. The proposed method shows improved accuracy when applied to staged fault data and fault-like load.

• 대한전기학회논문지:전력기술부문A
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• 제48권11호
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• pp.1365-1373
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• 1999

In many countries including Korea, in order to transmit the more electric power, the higher transmission line voltage is inevitable. So, a rapid reclosing scheme is important for EHV/UHV transmission lines to ensure requirements for high reliability of main lines. A critical aspect of reclosing operation is the extinction of the secondary arc since it must extinguish before successful reclosure can occur. Therefore the accurate simulation techniques of arcing faults are of importance. And successful reclosing switching can be accomplished by adopting a proper method such as HSGS and hybrid scheme to reduce the secondary arc extinction time. First of all, this paper discusses a suggested arc model, which have time dependent resistance for primary arc and piecewise linear approximated arc model for secondary arc. And this simulation technique is applied to Korean 765 kV transmission lines. Also hybrid scheme is simulated and evaluated for the purpose of shortening dead time. For adaptive reclosing scheme, variable dead time control algorithm is suggested. Two kinds of algorithm are tested. One is max tracking algorithm and the other is rms tracking algorithm. According to simulation results, rms tracking has less errors than max tracking. Therefore rms tracking is applied to Korean 765 kV transmission lines with hybrid scheme.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.163-165
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• 2002

In this paper a new numerical algorithm for fault distance calculation and arcing fault recognition based on one terminal data and derived in lime domain is presented. The algorithm is derived for the case of most frequent single-phase line to ground fault. The faulted phase voltage at the fault place is modeled as a serial connection of fault resistance and arc voltage. The fault distance and arc voltage amplitude are estimated using Least Error Squares Technique. The algorithm can be applied for distance protection, intelligent autoreclosure and for fault location. The results of algorithm tested through computer simulation are given.

• 대한전기학회논문지:전력기술부문A
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• 제54권2호
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• pp.61-66
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• 2005

This paper presents a refined protection algorithm of the unfused 22.9kV shunt capacitor banks in grounded wye connection to improve the existing algorithm using the voltage difference method. It is difficult to detect ground faults with arc near the input points or ground faults near the grounding point by the existing algorithm using only the voltage balanced relay. This paper shows that ground faults with arc near the input point can be detected by harmonics analysis of the differential voltage and that it has no impact of harmonics out of nonlinear loads which have the quantitative influence on capacitor banks. Thus the proposed method using harmonics analysis can be a proper detection method. In case of ground faults near the grounding point, an OVGR is being added recently and its validity is verified in this paper. The proposed method is applied to a 22.9kV example system and is verified that the proposed algorithm can detect clearly faults which are not easy to detect by the existing method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1642-1644
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• 1997

The simulation study of lightning faults reducing effects by the installation of surge arresters on the 154 kV transmission line is stated here. For the purpose of detailed simulation of arcing horn, a flashover model with dynamic characteristics of arcing horn gap was represented as a non-linear inductance which is controlled by EMTP/TACS(Electromagnetic Transient Program/fransient Analysis of Control Systems) switches. The back flashover inducing current was increased from 50 kA to 88 kA by the installation of surge arresters on the transmission line which has one ground wire and 20 ohms of tower footing resistances. The great advantage of surge arrester installation on one circuit of the double circuit transmission line is to prevent the simultaneous back flashover up to 190 kA.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 춘계학술대회 논문집 전기설비전문위원
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• pp.205-207
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• 2009

In 2007, 9,128 fires are attributed to electrical equipments. These fires resulted in 29 deaths and 262 injuries. Arc-faults were one of the major causes of these fires. When an unintended arc-fault occurs, it generates intense heat that can easily ignite surrounding combustibles. Conventional circuit breakers only respond to overloads, short circuits, and leakage currents. Therefore, the breakers do not protect against arcing conditions. This paper presents results obtained in experiments on ignition behavior of wire by series arc fault currents and techniques developed to detect the arc-faults. The developed technique was tested after installation to make sure they are working properly and protecting the circuit. If the developed arc detecting technique is applied, the electrical fires caused by an arc-fault can be reduced.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.737-739
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• 1996

Abnormal conditions and disturbances in distribution system cause an immediate influence to the customers. Conventional detection schemes for the distribution abnormalities have been applied in limited extents mainly because of their low reliability. In this paper, we developed a disturbance identification system which monitors the load level after a transient, checks the harmonic behavior of the load, and finally makes decision on the cause of the disturbance. This system identifies and discriminates overcurrent faults, arcing ground faults, recloser activities, and foreign object or tree contacts. In the implementation of the identification system, we applied fuzzy logic to better represent some variables whose Quantities are expressed only in non-numerical terms.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전력기술부문
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• pp.354-356
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• 2006

This paper presents a new one-terminal numerical algorithm for fault location estimation and for faults recognition. The proposed algorithm are derived for the case of most frequent single-phase line to ground fault in the time domain. The arc voltage wave shape is modeled numerically on the basis of a great number of arc voltage records obtained by transient recorder. From the calculated arc voltage amplitude it can make a decision whether the fault is permanent of transient. In this paper the algorithm uses a very short data window and enables fast fault detection and classification for real-time transmission line protection. To test the validity of the proposed algorithm the Electro-Magnetic Transient Program(EMTP/ATP) is used.

• 한국산학기술학회논문지
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• 제10권8호
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• pp.1810-1816
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• 2009

2007년도에 9,128건의 화재가 전기적인 원인에 의해서 발생되었고, 이들 화재에 의해 사망 29명과 부상 262명의 인명피해가 있었다. 아크고장은 전기화재의 주요 원인의 하나로, 일반적으로 높은 열을 발생시키며 쉽게 주변의 인화성물질을 점화시킨다. 그러나 기존의 차단기는 과전류, 단락전류, 누설전류에 대해서만 동작하기 때문에, 이에 대해서는 현재 특별한 보호책이 없는 실정이다. 본 논문은 직렬아크 고장전류에 의한 전선의 발화특성에 대한 실험에서 얻어진 결과를 통해 UL에서 제안하고 있는 기준이 국내의 현실에 적절하지 않음을 제시하였고, 이 결과를 기초로 개발된 기술의 동작특성 실험을 실시하여 아크고장회로를 보호할 수 있는지에 대한 신뢰성을 확인하였다. 모의실험을 통한 동작특성 분석결과, 개발된 아크고장 검출 기술을 적용하면 전기화재의 주요원인인 아크고장에 의한 화재를 현저히 저감시킬 수 있을 것으로 판단된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1843-1846
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• 1997

This paper describes the fault reducing effects of the 154 kV transmission tower by auxiliary grounding from the top of the tower to ground. The grounding surge impedance of the auxiliary grounding system is calculated by CDEGS(:Current Distribution Electromagnetic Interference Grounding and Soil Structure Analysis), and the critical lightning back flashover current and arcing horn dynamic characteristics are simulated by EMTP/TACS(:Electromagnetic Transient Program/Transient Analysis of Control Systems). The calculated results of total LFOR(Lightning Flashover Rate) shows that the LFOR can be reduced from 5.2(count/100km. year) to 3.4 by auxiliary grounding on the 154 kV transmission tower with one ground wire shielding system.