• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.287-287
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• 2008

HTS-케이블은 구리도체 대신 고온초전도도체를 사용하여 저항이 0이 되는 초전도현상을 이용하여 대용량 전력수송이 가능한 전력케이블로서 대도시의 전력부하 집중문제를 해결할 수 있는 환경 친화적 전력케이블이다. 최근 고온초전도선재의 고임계전류밀도화 및 장척화에 힘입어 HTS-케이블의 실용화를 목표로 경제성이 있는 전력케이블을 개발하려는 움직임뿐만 아니라 실증시험 등 활발한 연구가 진행 중이다. 그러나 초전도전력케이블에서 발생되는 교류손실은 케이블의 효율을 저하시킬 뿐만 아니라 냉동기비용 증가로 인한 기존 케이블과의 가격경쟁에서 경제성을 저하시키는 주된 요인으로 작용하기 때문에 이의 상용화에 앞서 교류손실에 대한 정확한 규명이 되어야 하며 또한 실계통 투입 시 중요한 선로임피던스에 대한 정확한 규명도 필요하다. 본 논문에서는 실제 한전 주관으로 고창시험장에 설치된 배전급 22.9 kV, 100 m, 50 MVA급 3 상 HTS-케이블에 대한 통전특성을 규명하기 위하여 먼저 HTS-케이블의 DC 통전특성을 조사하였다. 또한 3상평형운전상태에서 AC 통전특성(인덕턴스 및 교류손실)을 실험적으로 조사하였으며 5m-케이블에서 측정된 결과와 비교 검토하였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.6
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• pp.870-875
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• 2013

After introducing diagnosis equipment power failure prevention activities for distribution system have become more active. To do facility diagnosis and maintenance work more efficiently we need to evaluate reliability for the system and should determine the priority line with appropriate criteria. Thus, to calculate risk factor for the power distribution line that are composed of many component facilities its historical failure events for the last 5 years are collected and analysed. The failure statics show that more than 60% of various failures are related to environment factors randomly and about 20% of the failures are refer to the aging. As a strategic evaluation system reflecting these environmental influence is needed, a system on the basis of the probabilistic approach related statical variables in terms of failure rate and failure probability of electrical components is proposed. The figures for the evaluation are derived from the field failure DB. With adopting Bayesian rule we can calculate easily about conditional probability query. The proposed evaluation system is demonstrated with model system and the calculated indices representing the properties of the model line are discussed.

• KEPCO Journal on Electric Power and Energy
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• v.7 no.1
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• pp.171-177
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• 2021

In terms of distribution planning, accurate electric load prediction is one of the most important factors. The future load prediction has manually been performed by calculating the maximum electric load considering loads transfer/switching and multiplying it with the load increase rate. In here, the risk of human error is inherent and thus an automated maximum electric load forecasting system is required. Although there are many existing methods and techniques to predict future electric loads, such as regression analysis, many of them have limitations in reflecting the nonlinear characteristics of the electric load and the complexity due to Photovoltaics (PVs), Electric Vehicles (EVs), and etc. This study, therefore, proposes a method of predicting future electric loads on distribution lines by using Machine Learning (ML) method that can reflect the characteristics of these nonlinearities. In addition, predictive models were developed based on actual data collected at KEPCO's existing distribution lines and the adequacy of developed models was verified as well. Also, as the distribution planning has a direct bearing on the investment, and amount of investment has a direct bearing on the maximum electric load, various baseline such as maximum, lowest, median value that can assesses the adequacy and accuracy of proposed ML based electric load prediction methods were suggested.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.4
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• pp.60-67
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• 2004

With the proliferation of nonlinear loads, high neutral harmonic currents in three-phase four-wire distribution system have been observed It has been also known that the ground impedance has an effect on the neutral currents of a system which operates with harmonics present. On-site measurements of harmonic currents and voltages, and the soil resistivity and ground resistance under case study system were made and the corresponding equivalent circuit for the harmonics analysis was developed This equivalent circuit model was simulated numerically and graphically through the use of MATLAB and CDEGS software packages, and adequate results were obtained.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.420-421
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• 2008

배전설비의 안정성검토 및 조형물과 충분한 측방이격거리 확보검토를 위해 일반지역 직선선로에서 2400mm 완철을 설치한 보통장주와 편출장주 일반용 콘크리트 전주의 강도를 검토하였으며, 편출장주시 완철의 길이변화가 전주강도에 미치는 영향을 살펴보았다. 표준경간[3]에서 보통장주형태의 전주는 대용량선로의 전선(ACSR/AW-OC $240mm^2$)을 설치한 경우에도 허용강도이내였으며, 표준경간에서 편출장주 형태의 전주는 보통장주일때 보다 전주의 휨모멘트는 증가하였고 일반선로 ACSR/AW-OC$160mm^2$ 이하의 전선을 설치한 경우 허용강도를 갖게 됨을 알 수 있었다. 또한, 편출장주 완철의 길이를 2400mm에서 3200mm로 증가시킨 경우, 전주의 휨모멘트는 증가하였으며, 전주는 표준경간이 40M 이하에서 대용량선로의 전선을 설치한 경우에도 허용강도를 갖게 됨을 알 수 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.300-300
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• 2008

우리나라의 전기에너지 수요가 지속적으로 증가함에 따라 새로운 송배전 선로의 구축이 필요하다. 하지만 현재 도심지의 전력구에는 더 이상의 지중선의 증설은 불가능하며 가공선 설치의 경우 환경 민원의 부담을 떠안게 된다. 그래서 기존 동도체의 회선당 송전 한계를 극복하고 대용량 송전 및 손실을 크게 줄일 수 있는 초전도 케이블의 연구가 세계적으로 활발히 진행되고 있다. 한국전력 전력연구원은 신 전력시스템으로서의 22.9 kV급 초전도케이블 시스템을 고창전력시험센터에 설치하고 운영 및 유지 보수 과정을 통하여 실제 계통 적용을 위한 최적 운전조건을 연구하고 있다. 이 논문에서는 실제 부하 상황을 모의하기 위하여 초전도케이블의 장기 부하변동 시험에 따른 케이블 송전 능력 확인 및 냉각시스템의 반응성을 살펴보고 부하변동 시험 후 초전도케이블 도체 열화 여부를 확인하기 위하여 직류 임계전류를 측정하였다. 그 결과 부하변동 시험 전의 임계전류 값과의 변화율이 삼상 모두 ${\pm}1$% 내외로서 오차범위를 벗어나지 않으므로 건전한 것으로 판단되었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.17-26
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• 2018

If a photovoltaic (PV) system is installed in a primary feeder interconnected with the PV system, bi-directional power flow can occur, and then, the magnitude and direction of the fault current can change, depending on the fault location and point of common coupling (PCC) of the PV system, and the time current curve (TCC) cannot be properly coordinated between protection devices. Also, it is difficult to obtain a proper time interval for protection devices because the conventional setting approach is applied, even though the PV system is installed and operating. Therefore, this paper presents three operation modes considering the operational conditions of the PV system to obtain setting values for protection devices. Based on the mode, this paper proposes an algorithm to calculate the optimal protection coordination time interval according to the introduction capacity of the PV system. In addition, this paper performs modelling of a distribution system with the PV system and protection devices by using Off-DAS S/W, and analyzes the characteristics of the time interval between the protection devices, such as substation relays, reclosers, customer relays, and PV customer relays. The simulation results confirmed that the proposed operational modes and setting-value algorithms are useful and effective for protection coordination in a distribution system for a PV system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.77-86
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• 2020

Power quality problems caused by feeder voltage drop and extension construction cost problems can occur with the increasing utilization rates of the existing fixed-type EV (electric vehicle) charger. Moreover, EV users might not be able to access the EV charger due to a lack of EV charging facilities. Therefore, this paper proposes an MPSD (movable power supply device) for EVs to overcome user inconvenience caused by the insufficient number of chargers and extension cost issues. The proposed MPSD was mainly composed of a PV (photovoltaic) system, ESS (energy storage system), EV charging system, and monitoring and control system. Furthermore, there are three operation modes available to enhance the flexibility of the MPSD application, depending on the situation. This paper also presents an economical evaluation modeling using the present worth method to consider the cost and benefit elements. The simulation results based on proposed modeling showed that MPSD is more economical than the existing EV charger. Moreover, its profit can be increased significantly depending on the distance to the installation point.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.6
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• pp.440-448
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• 2009

Facility power-line electromagnetic interference (EMI) filters are used to provide radio frequency(RF) isolation between dedicated power distribution services and noise sensitive local power distribution systems. This type of EMI filters generally needs a high current capacity and, in some special applications, a high insertion loss of a minimum 100dB from 14kHz through 10GHz per MIL-STD 220 is required. This paper deals with an analysis and design of a wideband facility power-line EMI filter with the above requirements. The characteristics of the inductor and capacitor at high frequencies are investigated. The characteristics and design method of the facility EMI filter with a high order LC network are also presented. The prototype filter is finally implemented and its performance is verified from the experimental results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.36-40
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• 2009

Concrete poles(CP) are popular supports for distribution lines. Various types of grounding electrode, such as copper-clad rods, have been used to maintain CP's ground resistance under the required value. The buried part of CP can also have structural grounding effect because of its iron reinforcing rods inside CPs. In this paper, we measured the total ground current injected into CP ground while measuring the ground current splitting to the metal electrode as well as the total injecting current. By this, it was able to measure the ground current splitting to CP structure. Based on the measured results, interrelationship between ground resistance of metal electrodes and current split factor to CP structure was analyzed.