• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.153-154
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• 2015

Voltage Source Converter HVDC (VSC-HVDC) are a better alternative than conventional thyristor based HVDC systems. Unfortunately, VSC-HVDC's full potential cannot be utilized up till now due to absence of suitable HVDC protection. Recently, hybrid HVDC circuit breakers (HDCCB) have been developed and successfully lab tested. However, their application and feasibility in VSC-HVDC needs to be investigated. In this research paper we have modelled an existing HDCCB and evaluated its impact on fault reduction and interruption in VSC-HVDC systems. The HDCCB was applied in Korean Jeju-Haenam VSC-HVDC system model and its impact was analyzed for HVDC line-to-ground and line-to-line faults. HDCCB successfully interrupted the fault current and prevented the damages to costly IGBTs and converter transformers.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2054-2056
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• 1998

A conventional UPS can supply the clean power to the load. However, it may generate input current harmonics and the input power factor can be very poor. Therefore, the UPS itself may be a power interruption. This paper provides multifunctional converter of using single phase UPS. The proposed UPS can supply the clean power to the load without polluting the mains power system. The multi-functional converter provides battery charging, var compensation and harmonic suppression simultaneously. It was simulated to verify this work.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.67 no.1
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• pp.27-32
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• 2018

In this paper, we developed an algorithm to detect arc of PV power plant through frequency analysis. For arc detection based on frequency analysis, the filter should be designed to emphasize the difference between the arc state and the normal state. Therefore, in this paper, we analyzed the arc detection performance according to various filter structures. The arc detection algorithm developed in this paper extracts the filtering signal on current by using various filters and then calculates the frequency components and total energy using the FFT. In the final step, the arc is detected using the calculated energy magnitude. In order to verify the performance of the proposed arc detection algorithm, experiments were conducted on 51 kW solar inverters connected to power line. Through various experiments, it was confirmed that the proposed method effectively detects the arc.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.4
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• pp.143-151
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• 2000

Electric power distribution feeders are susceptible to faults caused by a variety of situations such as adverse weather conditions, tree contacts, equipment failure, accidents, etc. Distribution circuit faults result in a number of problems related to the reliability of service and customer power quality. In the distribution line, the permanent interruption of customer service resulting from a blown fuse or a recloser lockout was the only factor which was used to determine service reliability. On underground distribution line, the serving of cables by earth-moving equipment is a prevalent cause of faults and the most cable faults quickly develop into bolted current. we introduce th multi-circuit breaker coordination methods in the Underground Distribution Line.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.3
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• pp.155-158
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• 2006

$SF_6$ gas circuit breakers we widely used for short circuit current interruption in EHV or UHV power system. For a $SF_6$ gas circuit breaker development, the hot gas velocity measurement is necessary during $SF_6$ gas circuit breaker's trip operation. Small-gap flashover characteristics are used for this hot gas velocity measurement. This study sho was the hot gas velocity measurement results during $SF_6$ gas circuit breaker' trip operation.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.932-934
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• 1998

Electric power distribution feeders are susceptible to faults caused by a variety of situations such as adverse weather conditions, tree contacts, equipment failure, accidents, etc. Distribution circuit faults result in a number of problems related to the reliability of service and customer power quality. In the past, the permanent interruption of customer service resulting from a blown fuse or a recloser lockout was the only factor which was used to determine service reliability. So we developed KODAS(Korea Distribution Automation System) with successful and had fieid-testing of Distribution Automation System in last three years at Kang-dong Branch Office. In performing the project, KEPRI has gained valuable experience, through dealing with many difficult problem. This paper is depicted about the circuit breaker coordination problems in the Underground for the Distribution Automation Feeder.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.754-757
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• 1995

This system can detect a ground fault point or a bad insulated line by measuring a power plant DC feeder insulation resistance at the uninterruptible power status. And when the power plant DC feeder with low frequency AC signal has a ground fault, this measuring system can keep recording of its ground fault current and phase checked by Z.C.T. Therefore the power plant could protect a unexpected service interruption.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.152-157
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• 2005

Recently, higher speeds have been promoted in old overhead-lines. For high-speed operation in electric railways, increasing contact loss of the pantograph is one of the most important subjects. The contact loss causes power interruption and increases wear of contact strips and contact wires. In order to investigate the causes of contact loss and to work out effective improvement methods, theoretical analyses, experiments have been carried out. First of all, the wave propagating velocity (phase velocity) and characteristics of contact wire are one of the important indices for the current collecting performance. In this paper, mathematical formula arc derived for the prediction of the traveling wave velocity. The measured values in the experiment agree well with the theoretical predictions.

• Proceedings of the KIEE Conference
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• summer
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• pp.1106-1108
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• 2004

The arcing contact wear of circuit breakers can be the major cause for the maintenance requirement. The control of arcing times as short as possible but larger than the given minimum arcing time may be the effective way to mitigate the contact wear and to lessen the expenditure of a maintenance. In this paper the method for minimizing the arcing time is described. The basic concept used in the proposed method is the estimation of the current interruption instant from the informations such as the phase angle at the instant of trip commands and the magnitude of interrupted currents.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1483-1485
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• 2005

In recent years, customers and power supplies are interested in power quality. Demands of customers are change from standard quality of distribution power system to various high quality of distribution power system. so, it is necessary to apply power quality compensator. in our project, we develop the UPQC(Unfied Power Quality Compensator of 45kVA which compensates power factor and voltage sag, interruption. it is very frequently occurred power quality problems. As a series and shunt compensator, UPQC consists of two inverters with common dc link capacitor bank. It compensates the current quality in the shunt part and the voltage quality in the series part. In this paper, we present simulation and test result of developed UPQC system. Test for UPQC are performed at voltage sag, flickers and non-linear load conditions. For voltage sag and ficker generation, we use RTDS(Real Time Digital Simulator) and power amplifier system.