• Journal of the Korean Society of Safety
• /
• v.16 no.4
• /
• pp.96-102
• /
• 2001

In construction sites, portable generators and electrical equipments cause frequently electrical accidents due to the poor condition of their usage. However, there are very few technical guidelines on these equipments even though they have serious accident causing potentiality. In order to reduce such accidents in practical and economical, grounding methods are studied in this paper as the countermeasure of electrical accidents. Several Korean national standards and international standards regarding three grounding types are compared each other, and some prevention means of electrical accidents are reviewed in this study. This paper presents the most effective grounding methods by assuming the WCS with the isolated power systems.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.10
• /
• pp.73-77
• /
• 2010

Most accidents occurred in power receiving & transforming facility are ground fault. The quality of power supply is deteriorated since the ground fault is not detected promptly. This paper analyzes the problems about system-grounding type of 2 step power receiving & transforming facility, arrangement of protection relaying scheme and ground-fault protection system of ungrounded system. Then, this paper presents the arranging scheme of system-grounding type to improve power supply reliability.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.6
• /
• pp.1025-1033
• /
• 2010

This paper proposes a method to improve and analysis error cause of FI(Fault Indicator) information to be used for detecting fault section in distribution automation system. FI error cause is made by consideration fault current magnitude and time. So, a new method to prevent FI error is proposed to include fault current magnitude, time and direction. Therefore, it's considered network environments that grounded and ungrounded network in distribution automation system. The proposed method is proved by Matlap Simulink. By the result in this research, it's possible to quickly restoration, supplying stability and reliability power to customer.

• Proceedings of the KIEE Conference
• /
• 2000.11a
• /
• pp.43-45
• /
• 2000

In this paper, portable and vehicle-mounted generators grounding methods of low-voltage systems is compared to each other. Ungrouded system is better for the safety operation than solidly grounding system. This paper also determined the magnitude and duration of the permissible body current limit and step voltage for the solidly-grounding and ungrounded system.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.2
• /
• pp.285-292
• /
• 2011

DC traction power system is operated ungrounded so that minimize the stray current. Because the stray current is still present, a rail potential is increased. The ground faults in the DC railway systems are usually detected by a potential relay(64P). Moreover, if the rail potential goes high in the ordinary operating state because of the traction load, the potential relay would be maloperated. A presented protective relaying algorithm that can identify exactly the faulted region and can distinguish a ground fault from the potential rising of the rail is presented in this paper. This paper presents simulation technique that is very similar to the real operation situation using PSCAD/EMTDC.

• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.1948_1949
• /
• 2009

All the power generating station require dc auxiliary power systems to operate those dc components that must be available if a loss of ac power occur. Some examples of such components are auxiliary motors, circuit breakers, relays and solenoids. The dc source may be one common battery for both power and control or two separate batteries; one for power and another for control. Typically, a dc auxiliary power system is designed as an ungrounded system, instead of grounded system, so that a low-resistance ground fault on one of its two polarities will not affect the operation of the system, thus increasing system reliability and continuity of service. A ground detector should provide a high polarity-to-ground resistance so that a single ground fault occurring on the system will not affect the operation of that system. Sensitive relays have been known to energize momentarily while the cable and capacitive charge to ground shifts[1]. A power station had experienced this kind of incident and performed root cause analysis based on PC based simulation program known as PSpice. This simulation showed adapted relays on the system energize momentarily and design criteria on this relay should be corrected.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.54 no.9
• /
• pp.427-433
• /
• 2005

In DC tracking power supply system, ground faults are currently detected by the potential relay, 64P. Though 64P relay detects ground fault, it cannot Identify the faulted region which causes long traffic delays and safety problem to passengers. Two new ground fault protective relay schemes that can identify the faulted region are presented in this paper. One is bus differential protective relay and the other is ground overcurrent protective relay. Both type of relays is similar in principle to the ordinary bus differential protective relay and the ground overcurrent relay used in other power system. In DC traction power supply system, since it is ungrounded, ground fault current is not big enough to operate those relays. To solve the problem, a current control device, called device 'X', is newly introduced in both system, which enables large amount of ground fault current flow upon the positive line to ground fault. Algorithms for these relays are developed and their validity are verified by EMTP simulation.

• Journal of Electrical Engineering and Technology
• /
• v.3 no.3
• /
• pp.331-336
• /
• 2008

Electric load components have different characteristics according to the variation of voltage and frequency. This paper presents the load modeling of an electric locomotive by the parameter identification method. The proposed method for load modeling is very simple and easy for application. The proposed load model of the electric locomotive is represented by the combination of the loads that have static and dynamic characteristics. This load modeling is applied to the KTX in Korea to verify the effectiveness of the proposed method. The results of proposed load modeling by the parameter identification follow the field measurements very exactly.

• Proceedings of the KIEE Conference
• /
• summer
• /
• pp.566-568
• /
• 2004

최근 한국전력은 중국, 인도 둥 동남아시아 지역을 주요대상으로 자체개발한 종합배전자동화시스템을 수출하고자 활발하게 접촉하고 있다. 이들 대부분 수출대상 주요국가의 배전계통이 비접지로 운영하고 있어 배전계통 운영자의 공통된 관심사가 지락고장이 발생한 경우에 고장처리 방법이다. 비접지 계통은 단락고장의 경우 고장전류가 커 쉽게 고장구간 탐색이 용이하지만, 지락고장의 경우 고장전류가 매우 적어 배전자동화시스템에서 지원하는 고장처리 기능을 수행하기에 곤란하다. 따라서 해외시장의 기술적 우위확보와 종합배전자동화 시스템의 다목적 기능을 수행하고자 연구를 시작하였다. 지락고장이 발생하였을 때의 각종 파라메타를 중심으로 검토하였으며, 영상전압과 영상전류의 위상을 비교하여 고장구간 탐색기법을 제시하였다. 현재 연구결과를 바탕으로 현장실증시험이 진행되고 있다.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.155-156
• /
• 2008

비접지 계통에서 대부분의 고장은 1선 지락 고장이며 1선 지락 고장 시 고장 전류의 크기가 매우 작기 때문에 고장 검출에 어려움이 있다. 본 논문에서는 영상전류를 이용하여 새로운 FI 검출 알고리즘을 제안한다. 제안된 알고리즘은 선간전압과 영상전류만을 이용하여 단말에서 고장회선, 고장상, 고장구간을 한 번에 판별하여 FI를 검출한다. 제안된 알고리즘은 Matlab/Simulilnk를 통해 계통을 모의하여 검증하였다.