• 전기학회논문지
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• 제66권10호
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• pp.1454-1459
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• 2017

In spite of continuous increase of electric power demand and new generation plants, it is very difficult to install new transmission line. Therefore, it comes to be difficult to operate the power system stable, so it is required to find another way to get new transmission capacity. Because HVDC transmission system installation is the one of the best option for us, we have undertake the HVDC project in mainland. Buckdangjin-Goduck HVDC project(500kV, 3GW) is currently under construction and Eastern Power HVDC project(500kV, 8GW) is under the study for technical specification. Both of them have the Run-up SPS function for taking action of 765kV Transmission line fault. The Run-up SPS function increases the active power output of the HVDC rapidly when the transmission line between the power plant and network is tripped, thereby preventing the generator from overspeed and improving the power system stability. In this paper, we propose MEAC(Modified Equal Area Criteria) method based on traditional EAC method to quantitatively evaluate the effect of the HVDC run-up SPS function on the power system stability improvement.

• 조명전기설비학회논문지
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• 제25권4호
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• pp.97-103
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• 2011

The most important object of grounding systems is to protect human being from electric shock. Touch and step voltages are measured to evaluate the performances of grounding systems. Dangerous voltages have been largely studied by the power frequency fault currents, on the other hand, the ground current containing the high frequency components and surge currents haven't been considered. Many attempts about the grounding impedances reported in these days show that the performance of the grounding systems in high frequency range is very different with the ground resistance. It is necessary to analyze the dangerous voltages formed by the ground currents containing high frequency components. In this paper, the ground surface potential rises near the vertical and horizontal grounding electrodes are measured at the frequency of 100[Hz], 30[kHz], and 100[kHz]. Dangerous voltages are investigated with the frequency-dependent grounding impedance. As a result, the ground surface potential rise is increased as the grounding impedance increases. Touch and step voltages near the grounding electrode whose impedance increases with the frequency are sharply raised.

• 한국산학기술학회논문지
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• 제13권9호
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• pp.4146-4151
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• 2012

본 논문에서는 동적 부하를 고려한 전력계통의 과도 안정도 해석을 모의하고자 한다. 모터는 계통 부하의 주요부분을 차지하고 있으며 이들의 동적 부하 특성은 전력계통의 안정도 해석에 있어서 매우 중요한 요소이다. 전력계통의 안정도해석에서 개별 부하의 특성을 모두 반영할 수 없기 때문에 일반적으로 모터 부하를 일정 임피던스 부하로 취급하고 있다. 본 논문에서는 이러한 일반적인 방법으로 해결할 수 없는 개별부하의 특성을 고려해야만 하는 산업용 전력계통의 경우 모터의 동적 특성을 고려하여 안정도 해석을 수행하여 안정도 해석에 있어서 모터의 영향을 보였다. 대상은 실 계통인 광양제철소의 전력계통이며 3상고장에 의한 모터부하의 영향을 분석한다.

• 조명전기설비학회논문지
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• 제21권3호
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• pp.82-87
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• 2007

본 논문은 수용가에 대한 전력요금이 각 모선별로 부과될 경우 모선들의 전력품질을 측정하여 이를 비용화할 수 있다고 가정하였다. 이를 계통계획에 반영하여 예상되는 비용은 샘플계통을 통하여 다음과 같은 계산 방법을 제안하였다. 먼저 모선가격을 계산하기 위해서는 계통에서 전력설비의 운전조건은 최적조류계산에 의해 최적화되어 있는 상황으로 가정하여 모선가격[$/MVAH]을 산정하고, 계통의 각 모선에 연결된 부하들의 연중 발생하는 고장에 의해 탈락되는 피해비용을 산출하였다. 결과적으로 제안된 방법은 전력품질을 포함한 모선 총합 비용을 계산시 매우 효과적이였다.

• 조명전기설비학회논문지
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• 제25권1호
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• pp.85-92
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• 2011

The role of RCDs(Residual Current Protective Device) that are installed before the load is very important for preventing electric shock and electrical fire. However, although fault rate of RCD is increasing due to deterioration and long period usage, the RCD is permanently used without a checking of performance evaluation and it causes the electrical accident. In this paper, the amount of airborne chloride is researched in domestic costal area and the accelerated life test is conducted using a salt water spray tester in order to decide the life time of RCD. Aa a result of an accelerated life test, the MTTF(Mean Time To Failure) of RCD is 110.81 hours and B10 life time of RCD is 45.81 hours for the all samples. when an accelerated life test result is applied to within 2 km costal area, the life time of RCD is predicted about 5 years.

• 한국정보처리학회논문지
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• 제6권1호
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• pp.216-224
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• 1999

날로 더욱 복잡해지는 제어 컴퓨터의 고 신뢰성 확보를 위해 시간여분(time redundancy)의 일종인 rollback과 roll-forward 기법 등을 TMR 구종에 적절하게 혼용하는 두 가지 방법을 제안한다. Rollback과 roll-forward 기법은 약간의 추가시간만을 사용하여 재구성(reconfiguration) 없이도 일시적인 결함(fault)에 의해 발생한 TMR 고장(failure)의 회복을 위해 상호보완적으로 사용될 수 있다. 본 논문은 시스템의 고장상태확률의 유도를 통해 전체 작업의 평균실행시간이 최소가 되는 최적의 checkpoint 간격벡터를 유도한다. 수치예제를 통해 제안된 방법들이 다른 고장회복 기법을 적용했을 때와 비교하여 매우 효과적임을 보이고, 다양한 환경 하에서 여러 가지 최적의 checkpoint 간격벡터를 유도하였으며, 시뮬레이션을 통한 정량적 결과로써 그 우수성을 비교하고 검증하였다

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.470-473
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• 2000

Because of the continuous growth of energy consumption, and also the tendency to site power lines and pipelines along the same routes, the close proximity of high voltage structures and metallic pipelines has become more and more frequent. Moreover, normal steady state and fault currents become higher as electric networks increase in size and power. Therefore, there has been and still is a growing concern (safety of people marking contact with pipeline, risk of damage to the pipeline coating, the metal and equipment connected to pipeline. especially cathodic protection system) about possible hazards resulting from the influence of high voltage power system on metallic structures(gas pipeline, oil pipeline and water pipeline etc.). Therefore, we analyze the interference problems when the gas pipeline is buried with power cable in the same submarine tunnel. This paper present the results of the study about interference mechanism, AC corrosion, limitation of safety voltage and analysis of indiction voltage.

• 전기학회논문지
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• 제64권1호
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• pp.182-187
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• 2015

In the three-phase power system, when any one-phase or two-phases is open-phase, the unbalanced current flows and the single-phase power supplies to three-phase loads. Specially, motor coil and transformer coil receive over-current. As a result, great damage as well as electrical fire can occur to the power system. In order to improve these problems, this paper proposes that an open-phase detection device is designed by a new algorithm using electric potential difference between the resultant voltage of neutral point and ground, and a control circuit topology of open-phase protector is composed of highly efficient semiconductor devices. It improves response speed and reliability. The control algorithm circuit also operates the cut-off of a conventional residual current protective device (RCD) which flows an enforced leakage current to ground wire at open-phase accident. Furthermore, time delay circuit is added to prevent the incapable operation of open-phase protector about instantaneous open-phase not open-phase fault. The time delay circuit improves more reliability.

• Journal of Advanced Marine Engineering and Technology
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• 제36권7호
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• pp.935-941
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• 2012

This paper describes a study of conventional electrical rig and simulated application of Flywheel Energy Storage system on the power system of the offshore plants with dynamic positioning system with the following aims: improve fuel consumption on engines, prevent blackout and mitigate voltage sags due to pulsed load and fault. Fuel consumption has been analyzed for the generators of the typical drilling rigs compared with the power plant with Flywheel Storage Unit which has an important aid in avoiding power interruption during DP (Dynamic Positioning) operation. The FES (Fly wheel Energy storage System) releases energy very quickly and efficiently to ensure continuity of the power supply to essential consumers such as auxiliary machinery and thrusters upon main power failure. It will run until the standby diesel generator can start and supply the electric power to the facilities to keep the vessel in correct position under DP operation. The proposed backup method to utilize the quick and large energy storage Flywheel system can be optimized in any power system design on offshore plant.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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• pp.501-508
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• 2001

A graph or topographic map can often convey larger amounts of information in a shorter time than ordinary text-based methods. To visualize information precisely it is necessary to collect all the geological information at design stage, but actually it is almost impossible to bore or explore the entire area to gather the required data. So, tunnel engineers have to rely on the judgement of expert from the limited number of the results of exploration and experiment. In this study, several programs are developed to handle the results of geological investigation with various data processing techniques. The results of the typical case study are also presented. For the electric survey, eleven points are chosen at the valley to measure the resistivity using Schlumberger array. The measured data are interpolated in 3-dimensional space by kriging and the distribution of resistivity are visualized to find weak or fractured zone. The correlation length appears to be around 5 to 20 meter in depth. Regression analyses were performed to find a correlation length. No nugget effect is assumed, and the topographic map, geologic formation, fault zone, joint geometry and the distribution of resistivity are successfully visualized by using the proposed technique.