• 대한전기학회논문지:전력기술부문A
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• 제52권3호
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• pp.173-178
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• 2003

This paper proposes a three-winding transformer protective relaying algorithm based on the ratio of the induced voltages (RIV). The RIV of the two windings is the same as the turn ratio for all operating conditions except an internal fault. For a single phase and a three-phase transformer containing the wye-connected windings, the induced voltages of the windings are estimated. For a three-phase transformer containing the delta-connected windings, the induced voltage differences are estimated using the line currents, because the winding currents are practically unavailable. The algorithm can identify the faulted phase and winding if a fault occurs on one phase of a winding. The test results clearly show that the algorithm successfully discriminates internal winding faults from magnetic inrush. The algorithm not only does not require hysteresis data but also can reduce the operating time of a relay.

• 전기학회논문지
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• 제61권7호
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• pp.937-943
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• 2012

Most of faults occurred in transmission lines are single-phase to ground faults and transient faults. Single-phase auto reclosing is an appropriate scheme to maintain the system stability and restore the system effectively when those faults are occurred. In single-phase auto reclosing scheme, the secondary arc is generated after faulted phase is tripped to eliminate the fault and it is sustained by the capacitive and inductive coupling to the healthy phases. It is important to reclose the faulted phase after fully extinction of secondary arc because of the damage applied to system. Therefore, it is necessary to research on the detection of secondary arc extinction to ensure high success rate of reclosing. In this step, firstly, the accurate modelling of secondary arc should be performed. In this paper, the modelling of secondary arc is performed by using EMTP-RV and the simulation results show that the implemented model is correct and effective.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 D
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• pp.2196-2198
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• 2001

Because the circuit board has the structure connected by circuit patterns, the work to test whether the analog devices or circuits such as resisters, capacitors, inductors, diodes, etc. on the tested board is goof or not is very difficult. This paper proposes the test method of identifing the faulted devices or faulted circuit on the circuit board using guarding circuit. The guarding method is the techniqus measuring accurately the value of the devices by separating the electronic devices to be tested from around it. Finally, the availability and accuracy of the proposed test method is verified by applying the technique to a test electronic circuit.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
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• pp.243-245
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• 2004

This paper proposes the discrimination method for the fault location, whether it is within the line where the distributed generation(DG) is integrated or out of the line (but sharing the same bus of the substation). In general, DG has to be disconnected from the grid when the fault occurs on the interconnected distribution feeder as soon as possible. However, the faults occured on the neighboring feeder would mistakenly cause the disconnection of the DG. For reliable operation of DG, DG should be sustained at the fault occurred on neighboring distribution feeders. The proposed identification method utilizes the impedance monitored from the DG and examines the coordination of overcurrent relay of the distribution system. This paper describes how the proposed method to identify the faulted feeder and how the method can be utilized.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.1173-1174
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• 2013

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.445-450
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• 1989

In this study, a variety of method to diagnose a fault of rotatory machine is suggested. Apprehending the physical meaning of each techniques, computer simulation is performed. The result from this computer simulation and the signal of the faulted ball bearing is studied from all its aspect. It is found that this conditioning monitor system is effective.

• Journal of Electrical Engineering and Technology
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• 제1권2호
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• pp.137-144
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• 2006

This paper proposes novel protection schemes for grid-connected distributed generation (DG) units using the fault location algorithm. The grid-connected DG would be influenced by abnormal distribution line conditions. Identification of the fault location for the distribution lines at the relaying point of DG helps solve the problems of the protection relays for DG. The proposed scheme first identifies fault locations using currents and voltages measured at DG and source impedance of distribution networks. Then the actual faulted feeder is identified, applying time-current characteristic curves (TCC) of overcurrent relay (OCR). The method considering the fault location and TCC of OCR might improve the performance of the conventional relays for DG. Test results show that the method prevents the superfluous operations of protection devices by discriminating the faulted feeder, whether it is a distribution line where DG is integrated or out of the line emanated from the substation to which the DGs are connected.

• 대한전기학회논문지:전력기술부문A
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• 제54권9호
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• pp.427-433
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• 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.

• 동굴
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• 제75호
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• pp.15-20
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• 2006

이 논문의 목적은 추가령 열곡 내에 발달한 단층구조를 확인하려는 것이다. 열곡에 관한 이해는 한국의 구조지형 발달에 관한 실태를 파악하는데 매우 중요한 의미를 갖는다. 그러나 아직까지 열곡형성에 관한 메카니즘이나 형성과정에 관한 논의가 확실하게 정리되지는 않았다. 야외조사를 통해서 얻은 자료를 기초로 하면 이 지역에 단층구조가 존재하는 것이 확실하다. 그러나 열곡이 매우 길고 넘어서 단층구조 전체에 대한 증거를 확인하기는 매우 어려운 점이 있다. 이 연구에서 IMAGEM은 매우 유용한 방법론의 하나이다. IMAGEM은 Electomagnetic Instrument Inc. 에 의해 개발되었고 $0.001{\sim}20,000Hz$를 커버한다.

• 전기학회논문지
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• 제61권3호
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• pp.373-379
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• 2012

This paper presents a fault location algorithm based on the adaptively estimated value of the local sequence source impedance for faults on a parallel transmission line. This algorithm uses only the local voltage and current signals of a faulted circuit. The remote current signals and the zero-sequence current of the healthy adjacent circuit are calculated by using the current distribution factors together with the local terminal currents of the faulted circuit. The current distribution factors consist of local equivalent source impedance and the others such as fault distance, line impedance and remote equivalent source impedance. It means that the values of the current distribution factors can change according to the operation condition of a power system. Consequently, the accuracy of the fault location algorithm is affected by the two values of equivalent source impedances, one is local source impedance and the other is remote source impedance. Nevertheless, only the local equivalent impedance can be estimated in this paper. A series of test results using EMTP simulation data show the effectiveness of the proposed algorithm. The proposed algorithm is valid for a double-circuit transmission line system where the equivalent source impedance changes continuously.