• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 추계학술대회 논문집
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• pp.69-72
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• 1998

A study to identify the energized status of the 22.9kV underground power cable by the detection of vibration was reformed. We derived that there exists vibration at double the line frequency in live cables by electromagnetic force. The vibration can be picked up by accelerometer sensor. A prototype was tested on the underground distribution system in Chonan Station, KEPCO. The results are presented and suggest the applicability of the detecting device.

• 대한전기학회논문지:전력기술부문A
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• 제51권10호
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• pp.525-533
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• 2002

It is common to install multiple lines in the same route. Recently, excessive sheath circulating current was partially measured in underground cable systems of KEPCO. Especially, the installation type, unbalance section length between joint boxes and zero sequence current by distribution cable have an effect on the rising of sheath circulating current in the underground transmission system. If excessive current flows in sheath, sheath loss which is reduced the transmission capacity is produced. This paper describes the relation analysis of sheath circulating current and burying types. And also, a detailed analysis on rising cause and characteristic of sheath circulating current by considering various unbalanced conditions presents using analysis and measurement regarding cable systems which have the problem of excessive sheath circulation current.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.459-461
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• 2005

This paper analyses the induced voltage characteristic of CCPU with unbalanced current from distribution line on underground transmission power cable systems. In switching surge strokes, in order to obtain the data of induced voltage/current on CCPU, the actual proof test carried out. This paper is expected to contribute the establishment of proper protection methods of CCPU against the unbalanced current from distribution line on underground transmission power cable systems.

• 전기학회논문지
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• 제60권12호
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• pp.2333-2338
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• 2011

In this paper, we develope a wavelet transform based time-frequency domain reflectometry (WTFDR) for the fault localization of underground power cable. The conventional TFDR (CTFDR) is more accurate than other reflectometries to localize the cable fault. However, the CTFDR has some weak points such as long computation time and hard implementation because of the nonlinearity of the Wigner-Ville distribution used in the CTFDR. To solve the problem, we use the complex wavelet transform (CWT) because the CWT has the linearity and the reference signal in the TFDR has a complex form. To confirm the effectiveness and accuracy of the proposed method, the actual experiments are carried out for various fault types of the underground power cable.

• 조명전기설비학회논문지
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• 제28권6호
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• pp.60-67
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• 2014

Power system fault analysis is commonly based on well-known symmetrical component method, which describes power system elements by positive, negative and zero sequence impedance. The majority of fault in transmission lines is unbalanced fault, such as line-to-ground faults, so that both positive and zero sequence impedance is required for fault analysis. When unbalanced fault occurs, zero sequence current flows through earth and ground wires in overhead transmission systems and through cable sheaths and earth in underground transmission systems. Since zero sequence current distribution between cable sheath and earth is dependent on both sheath bondings and grounding configurations, care must be taken to calculate zero sequence impedance of underground cable transmission lines. In this paper, EMTP-based sequence impedance calculation method was described and applied to 345kV cable transmission systems. Calculation results showed that detailed circuit analysis is desirable to avoid possible errors of sequence impedance calculation resulted from various configuration of cable sheath bonding and grounding in underground cable transmission systems.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.558-560
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• 2003

The effects of surge arresters for protection of transmission systems against direct lightning strokes have already been investigated using the digital simulation program EMTP. Distribution lines are spanned on a much large area as compared to transmission lines, and therefore, are more often susceptible to lightning strokes. This paper analyzes the overvoltages on underground cable system against direct lightning strokes to the overhead ground wire using the digital simulation. The effects of lightning protection methods, such as lowering the grounding resistance and installing the surge arrester, for preventing overvoltages on underground cable system caused by direct lightning strokes to the overhead ground wire is investigated. Several schemes have been proposed to protect underground cables. This paper summarizes the main results of a study aimed at analysis of lightning overvoltages in variety underground feeders protected by metal-oxide arresters. This study will provide insulation coordination methods for reasonable system design in 22.9kV underground cable system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.601-604
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• 2001

The insulation materials of cables used for underground power transmission requires a higher insulating capability. and the most popular method to examine the cable is partial discharge test due to applying variation voltage. In the thesis. air void. silicone oil. of which may possibly exist real cables. are simulated by Electra 2D program. Also the relations between calculated field strength and the void defect type in the cable joint materails. In the modeling. electic field inner to the cable joint material composed by XLPE and EPDM is modeling simulated. We obtained the electric field distribution in void due to two conditions.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.601-604
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• 2001

The insulation materials of cables used for underground power transmission requires a higher insulating capability, and the most popular method to examine the cable is partial discharge test due to applying variation voltage. In the thesis, air void, silicone oil, of which may possibly exist real cables, are simulated by Electro 2D program. Also the relations between calculated field strength and the void defect type in the cable joint materials. In the modeling, eclectic field inner to the cable joint material composed by XLPE and EPDM is modeling simulated. We obtained the electric field distribution in void due to two conditions.

• 조명전기설비학회논문지
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• 제22권2호
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• pp.107-113
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• 2008

22.9[kV]-y 배전 방식은 지중 케이블로 전력을 공급하고 있으며 선로 운영상 배전케이블 선로의 동심중성선을 케이블 접속 구간마다 3선 일괄 접지하는 다중 접지방식을 채택하고 있다. 그러나 지중 배전 선로에서 각 상의 부하가 평형일 경우에도 동심중성선에는 부하 전류의 약 40[%](전력구)${\sim}$50[%](관로)의 동심중성선 순환 전류가 발생되고 있기 때문에, 순환전류로 인한 손실이 도체 손실의 76[%]에 달한다. 이러한 손실 전력으로 케이블의 내부온도가 상승되어 케이블의 허용전류 용량이 관로의 경우 20[%] 정도 감소하게 된다. 본 논문은 이와 같은 문제점을 해결하기 위하여 새로운 동심중성선 접지방식을 제안하고 있다. 새로운 방법은 동심중성선의 순환전류를 효과적으로 제거하고 있으며, 그 방안을 직접 계통망에서 적용시켜서 실측하여 본 결과, 그 타당성과 유용성을 확인하였다.

• 전기학회논문지
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• 제56권12호
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• pp.2091-2097
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• 2007

This paper described the verification of modeling technique of underground distribution from comparison between field test and simulation. It needs more exact transient phenomenon analysis model to establish lightning protection of underground distribution line. Although, there were a lot of transient phenomenon researches, nobody could has verified the confidence of modeling from field tests in interior until now. So, simulation model verified field test is needed to analyse transient phenomenon of underground distribution system. The examination must be accomplished in many different condition before suggesting these verified analysis model. In this paper, the conditions were examined and the various data results on the different line composition was compared with the EMTP simulation, when the lightning impulse test was accomplished at underground distribution line. Also the value between field test and simulation was very closed and the method of modeling has demonstrated confidence, when the method is used to analyse domestic transient phenomenon of underground distribution.