• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.73-74
• /
• 2007

For a safe operation of HVDC systems, the fault location and clearance of faults in the HVDC lines are important. Past methods for fault location on HVDC cable depend on existence of assistance cables and fault resistance, broken cable and environment of fault location. For complement these problems, in this paper, fault location method using traveling wave and cross correlation function is proposed for HVDC cables. Voltage controlled source and current controlled source HVDC were modeled by EMTDC/PSCAD. The proposed algorithm were verified varying with fault distance, fault resistance.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.913-914
• /
• 2007

Power transformer shall be designed and constructed to withstand the mechanical and thermal stresses produced by external short circuits which include three-phase, single line to ground, double line-to-ground, and line-to-line faults on any one set terminals at a time. This paper presents the method of short-circuit test and means of evaluation during and after each test to judge the results of short-circuit tests.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.1948-1949
• /
• 2007

This paper presents the characteristics and effects of grounding resistor and impedance. In grounding system, Grounding resistor is governed neutral currents and voltage. It seems that, grounding resistor has 0 value, then circuit has no faults. While if grounding resistor has large value, then neutral current has large value of fault current and it is made a damage to the utility. In order to analyze the grounding impedance characteristic, EMTP simulation has been used. The grounding impedance characteristic has been analyzed and tested for various grounding arrangements and electrode circuit shapes.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.1063-1064
• /
• 2007

본 연구는 유도전동기 진단시스템을 개발하기 위하여 테스트 전동기 내부에 취부된 자속센서 신호를 사용한 알고리즘 적용 결과를 논한 것으로서 분류기별 고장 판별 정확도에 대하여 서술하였다. 특징추출은 Kernel Principal Component Analysis (KPCA) 방법을 이용 하였으며, 테스트 샘플들에 대해서는 LDA(Linear Discriminant Analysis)와 k-NN(k-Nearest neighbors) 분류기법을 이용하여 판별하였다. 회전자 바 손상이나 편심(동적/정적)인 경우는 두 가지 분류기 모두 95[%]이상의 높은 분류 정확도를 보였지만, LDA인 경우 정상상태를 비롯한 베이링 불량이나, 샤프트 변형인 경우는 낮은 분류율을 보였다.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.675-676
• /
• 2007

This Paper presents circuit improvement of 345kV Bus bar protection panel by using VDD (Voltage disturbance detection) relay with distinctive ability between human error in the field test and real facility faults. Therefore, We expect that this improvement of circuit helps decrease of blackout coming from human error. In order to guarantee electric power system reliability, consistent study of human error prevention in the event of field test is necessarily required

• Proceedings of the KIEE Conference
• /
• 2003.11c
• /
• pp.571-574
• /
• 2003

This paper proposes a detection method for mechanically stuck control rod drive mechanism (CRDM) faults. During the normal operation of a CRDM, disturbance voltage is induced due to the change of the airgap flux between the stator and the armature of a CRDM. This disturbance voltage is estimated by using $H_\infty$ filtering method, and generalized plant is used in linear fractional transform (LFT) framework. $H_\infty$ filtering is described and solved in terms of linear matrix inequalities (LMIs). Simulation results are shown.

• Proceedings of the KIEE Conference
• /
• 2004.11b
• /
• pp.14-16
• /
• 2004

A DC railway system has low feeder voltage, The remote fault current can be smaller than the current of load starting. So it is important to discriminate between the small fault current and the load starting current. The load starting current increases step by step but the fault current increases all at once. As for the load starting current, the time constant of load current at each step is much smaller than that of the fault current. To detect faults in DC railway systems, an algorithm using the time constant calculated by the method of least squares was presented. But, It have a weakness about harmonic to calculate time constant. So in this paper, new protection algorithm for DC railway systems using estimation of time constant based on fourier transform was presented.

• Proceedings of the KIEE Conference
• /
• 2006.07e
• /
• pp.87-88
• /
• 2006

There are a number of reported instances of actual pipeline rupture during power line faults caused by melting of the pipe wall. This type of hazard was considered to be among the most serious of AC effects on pipelines in an international survey, comparable to the personnel safety hazard. Moreover, resistance coupling is not only a risk when the pipeline parallels a power line but also when they cross. One method of minimizing the effects of resistive coupling is by maintaining an appropriate separation distance between the pipeline and tower. This paper investigate the experiment for separation distance between the powerline earth and pipelines.

• Proceedings of the KIEE Conference
• /
• 2005.07b
• /
• pp.984-986
• /
• 2005

변압기 권선내에서 발생되는 고장을 유한요소 전자계해석 프로그램(FLUX2D)을 이용하여 해석하였다. 50kVA, 13200/230(V) 단상 변압기의 권선간 고장시 전자계해석을 1차측 권선고장(turn-to-earth)과 2차측 권선고장(turn-to-turn)을 모의하여 해석하였다. 권선내부 고장 및 2차측 단락시 누설 자속분포, 권선간의 힘의 분포, 변압기 내부 권선의 정상시와 단락시의 전자계비교, 단락권선과 권선 상호간의 전자계 해석을 통하여 변압기에 미치는 영향을 해석하였다. 변압기 권선간 단락시의 전자력 분석결과는 변압기의 절연설계 및 단락기계력에 대한 프레임 구조 설계를 위한 자료로 활용될 수 있다.

• Proceedings of the KIEE Conference
• /
• 2005.07b
• /
• pp.1047-1049
• /
• 2005

Hydraulic power plant is operated for peak load and frequently start-stop because of no continuous operation. So the fault can happen due to field voltage swing in the middle of starting or reactive power swing on the line. On this research, we want to analyze that this status influence on line and generator. we hope this research can contribute to the power quality improvement.