• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전력기술부문
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• pp.344-346
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• 2005

The recovery time of developing SFCL(Superconducting Fault Current Limiter) has an uncertainty. In general, the recovery time is estimated at 1 sec and more, even though the progress of SFCL technology is considered. However, auto reclosing time of circuit breaker is 0.5 sec in Korean distribution power system. It is impossible to apply only one SFCL to power system because the recovery time is over the reclosing time of protection system. This study proposes a new SFCL system for distribution power system application. The proposed systems consider auto reclosing action for the protection in practical power system and consist of tow parallel SFCLs.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.1617-1618
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• 2015

This paper analyzed catenary impedance characteristics of relays installed in substation and sectioning post to protect power feeding circuit in the extended power feeding conditions. For this, we modelled AT feeding system using PSCAD/EMTDC and calculated catenary impedance. The relay installed in substation calculated catenary impedance of the extended power feeding area adding catenary impedance of self protection zone. But, the relay installed in sectioning post calculated catenary impedance of the only protection area. Therefore, we confirmed that the more reliable protection way can be utilized using the relay installed in sectioning post.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
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• pp.285-288
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• 2008

Even though many modular converters have several internal protection circuit blocks for various abnormal operation conditions, there are many failure cases on modular converters at real applications. In this paper, the control strategy for failure protection of converters with internal 'In-Hibit' function is investigated. As an example, for the MDl modular converters the in-hibit function application is realized and the test results shows that adopting in-hibit function while converter switching reduces the voltage and current stress. And the reduction of switching stress on converter will decrease failure rate on converters.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.415-418
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• 2002

In the paper, a four-phase 16/12 structure Switched Reluctance motor drive is presented. The construction of the stator and the rotor in the motor, the scheme of the rotor position detector and the main circuit of the power converter are described. The comparison of the four-phase 16/12 motor and the four-phase 816 motor and the comparison of the four-phase 16/12 motor and the three-phase 12/8 motor are made. In the controller, the PWM control variable-speed control, the commutation control, the four quadrants control, the overvoltage protection, the overcurrent protection and the under voltage protection could be achieved. Tested results of the developed prototype are made.

• 한국산학기술학회논문지
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• 제7권1호
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• pp.52-56
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• 2006

본 논문에서는 산악지형이 많은 한반도에서 전파의 다중경로 전달 특성을 분석하여 최적의 레이다 운용 사이트를 선정하고 레이다에 발생되는 전파를 효율적으로 관리함으로써 레이다 운용을 적에게 최소로 노출시켜 대방사미사일의 공격을 피하면서 원하는 정보를 충분히 획득하는 전자보호 기술에 대해서 기술하였다. 또한 다중 경로에 의한 전파의 위상 특성을 분석하여 전력밀도의 변화를 분석하였다.

• 대한전기학회논문지:전력기술부문A
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• 제54권12호
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• pp.580-585
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• 2005

The recovery time of developing SFCL(Superconducting Fault Current Limiter) has an uncertainty. In general, the recovery time is estimated at 1 sec and more, even though the progress of SFCL technology is considered. However, auto reclosing time of circuit breaker is 0.3 or 0.5 sec in Korean power system. It is impossible to apply only one SFCL to power system because the recovery time is over the reclosing time of protection system. This study proposes two new SFCL systems for power system application. The proposed systems consider auto reclosing action for the protection in practical power system and consist of tow parallel SFCLs.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 추계학술대회 논문집
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• pp.215-217
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• 2008

This paper suggests a overvoltage protection scheme for HID lamp. HID lamp has complex characteristics and long duration in process from starting to steady state condition. So it is necessary to protect both starting and normal lighting mode. The protection method is composed of two circuit: one is for ignition state and the other is for steady state.

• Journal of Power Electronics
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• 제16권1호
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• pp.362-373
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• 2016

The on-line measurement of high-power IGBT collector current is important for the hierarchical control and short-circuit and overcurrent protection of its driver and the sensorless control of the converter. The conventional on-line measurement methods for IGBT collector current are not suitable for engineering measurement due to their large-size, high-cost, low-efficiency sensors, current transformers or dividers, etc. Based on the gate driver, this paper has proposed a current measuring circuit for IGBT collector current. The circuit is used to conduct non-intervention on-line measurement of IGBT collector current by detecting the voltage drop of the IGBT power emitter and the auxiliary emitter terminals. A theoretical analysis verifies the feasibility of this circuit. The circuit adopts an operational amplifier for impedance isolation to prevent the measuring circuit from affecting the dynamic performance of the IGBT. Due to using the scheme for integration first and amplification afterwards, the difficult problem of achieving high accuracy in the transient-state and on-state measurement of the voltage between the terminals of IGBT power emitter and the auxiliary emitter (u_Ee) has been solved. This is impossible for a conventional detector. On this basis, the adoption of a two-stage operational amplifier can better meet the requirements of high bandwidth measurement under the conditions of a small signal with a large gain. Finally, various experiments have been carried out under the conditions of several typical loads (resistance-inductance load, resistance load and inductance load), different IGBT junction temperatures, soft short-circuits and hard short-circuits for the on-line measurement of IGBT collector current. This is aided by the capacitor voltage which is the integration result of the voltage uEe. The results show that the proposed method of measuring IGBT collector current is feasible and effective.

• 전기학회논문지
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• 제62권4호
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• pp.584-590
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• 2013

Depending on the operating characteristics, track circuit is installed for the purpose of control directly or indirectly of the signal device, point switch machine and other security device. These are mainly used for train detection, transmission of information, broken train detection and transmission of return current. Especially, the return current is related to signal system, power system and catenary line, and track circuit systems. It is one of the most important component shall be dealt for the safety of track side staff and for the protection of railway-related electrical system according to electrification. Therefore, an accurate analysis of the return current is needed to prevent the return current unbalance and the system induced disorder and failure due to an over current condition. Also, if the malfunction occurred by the return current harmonics, it can cause problems including train operation interruption. In this paper, we presented measurement and analysis method at return current and it's harmonics by train operation. By the test criteria, we evaluated for safety. Hereafter, it is expected to contribute to the field associated with it.

• 조명전기설비학회논문지
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• 제25권9호
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• pp.75-79
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• 2011

The MOV(Metal Oxide Varistor), a voltage limiting element, has been installed in the SPD(Surge Protective Device) or inside the internal circuit of an electronic appliance for protection of the electric power system and electronic device against electrical surge. Such an MOV is exposed, however, to the risk of the thermal runaway resulting from excessive voltage and deterioration. In this paper, a reciprocal action has been tested and analyzed using a phosphorus bronze switching module and the low-temperature solder. And a short current break characteristic test linked with the circuit breaker has been performed to limit the inrush current when the MOV breaks down. It has been proven that the phosphorus bronze switching module installed inside the internal circuit can improve the safety of the power line system and the electronic device.