• 방송공학회논문지
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• 제25권1호
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• pp.13-24
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• 2020

한국에는 전력 분배를 위하여 약 9백만 개의 전신주와 1.3백만 킬로미터의 송전선이 있다. 이러한 많은 전력 설비의 유지보수를 위해서는 많은 인력과 시간이 소요된다. 최근 인공지능을 사용한 여러 고장진단 기술들이 연구되어 오고 있기 때문에 본 논문에서는 송전선의 여러 요인으로 인한 늘어짐을 감지하기 위해 기존의 현장에서의 검증 방법이 아닌 카메라 시스템으로 촬영한 영상에서의 인공 지능 기술을 활용한 송전선 늘어짐 감지 시스템을 제안한다. 제안하는 시스템은 (i) 객체 탐지 시스템을 이용한 송전탑 감지 (ii) 동영상 촬영 데이터의 화질 저하 문제를 해결하기 위한 히스토그램 평활화 기법 (iii) 송전선 전체를 파악하기 위한 파노라마 영상 스티칭(iv) 송전선 탐지 알고리즘 적용 후 파노라마 영상 스티칭 기술을 이용한 늘어짐 판단 과정으로 진행된다. 본 논문에서는 각각의 과정들에 대한 설명 및 실험 결과를 보인다.

• Journal of Power Electronics
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• 제18권1호
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• pp.234-250
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• 2018

This paper presents a new load sharing control for use between paralleled three-phase inverters in an islanded microgrid based on the online line impedance estimation by the use of a Kalman filter. In this study, the mismatch of power sharing when the line impedance changes due to temperature, frequency, significant differences in line parameters and the requirements of the Plug-and-Play mode for inverters connected to a microgrid has been solved. In addition, this paper also presents a new droop control method working with the line impedance that is different from the traditional droop algorithm when the line impedance is assumed to be pure resistance or pure inductance. In this paper, the line impedance estimation for parallel inverters uses the minimum square method combined with a Kalman filter. In addition, the secondary control loops are designed to restore the voltage amplitude and frequency of a microgrid by using a combined nominal value SOGI-PLL with a generalized integral block and phase lock loop to monitor the exact voltage magnitude and frequency phase at the PCC. A control model has been simulated in Matlab/Simulink with three voltage source inverters connected in parallel for different ratios of power sharing. The simulation results demonstrate the accuracy of the proposed control method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1186-1188
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• 1999

When we perform the test related to the power distribution system such as artificial fault test, protective coordination test, distribution automation test in short length test line, Lumped Constant Circuit, a kind of variable impedance, should be attached to the test line in order to make it equivalent to a real line in length electrically. In this paper we designed the positive sequence and zero sequence Lumped Constant Circuit with optimized inductor and resister for the modification of long, 16km, distribution line, when they are attached to the short, 4km, distribution test line.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.199-201
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• 2003

Because of Korean power system characteristics and increasing power demand, the need of 765kV transmission line is growing gradually. Now a days, KEPCO's 765kV transmission line has been tested and stands for commercial operation. During the first stage, 765kV transmission line will be operated with two voltage grades of 765kV and 345kV, which results the unbalance of power system. So unbalanced current such as zero sequence current flows in the transmission line. In this paper, we describes the simulation study of 765/345kV parallel transmission line by using EMTDC program.

• Journal of Electrical Engineering and Technology
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• 제7권1호
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• pp.103-108
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• 2012

The present study describes the considerations on the long-term reliability of the on-line partial discharge (PD) ceramic sensor for thermal power generators. Voltage acceleration aging tests were carried out under continuous and impulsive thermal aging at more than $100^{\circ}C$, considering the practical service environment. Experimental results show that the sensors have a life that could last for more than 100 years, excellent dielectric characteristics, and insulation strength. In addition, the ceramic on-line PD sensors were installed in a thermal power generator in Korea for demonstration. The results of the PD calibration and test voltage application prove that the on-line ceramic sensors have satisfactory performances for on-line PD measurement.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.569-575
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• 2001

The three-phase diode rectifier with capacitive Inter is highly sensitive to line voltage unbalance. Because of its inherent nonlinear characteristics small line voltage unbalance may cause highly unbalanced line current causing detrimental effects on power quality. This paper presents a theoretical basis on this 'unbalance amplification effect' and derives an analytical model of line current characteristics under unbalanced line voltage condition for various modes of operation. The results provide a basic and important guideline for optimal design of a three-phase diode rectifier with capacitive filter that is most commonly used for interfacing various power conversion equipments to power lines.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.723-724
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• 2007

Live line work is well known for mending and maintenance of electrical power equipment. Nowadays needs of electric power supply quality require live line work In Korea, live line work is needed since 765kV transmission operation and restructure of electric power industry has changed. In other words, in case of suspension of power supply on the transmission is getting hard to keep up with efficiency of transmission operation, customer's confidence and generation-limited cost. Therefore live line work is very meaningful. As the condition of 765kV Transmission both bare hand and Helicopter live line technique must be used in moderation because of economic, geographical, environmental circumstances around steel tower.

• Journal of Electrical Engineering and Technology
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• 제8권4호
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• pp.694-703
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• 2013

In electric power system, the line stability indices adopted in most of the instances laid stress on variation of reactive power than real power variation of the transmission line. In this paper, a proposal is made with the formulation of a New Voltage Stability Index (NVSI) which originates from the equation of a two bus network, neglecting the resistance of transmission line, resulting in appreciable variations in both real and reactive loading. The efficacy of the index and fuzzy based load flow are validated with IEEE 30 bus and Tamil Nadu Electricity Board (TNEB) 69 bus system, a practical system in India. The results could prove that the identification of weak bus and critical line in both systems is effectively done. The weak area of the practical system and the contingency ranking with overloading either line or generator outages are found by conducting contingency analysis using NVSI.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권5호
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• pp.206-212
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• 2005

In this paper, criterion and algorithm for on-line dissolved gas of a Power transformer are studied. For the initial diagnosis of a power transformer, the on-line dissolved gas analysis is one of the most important and acceptable item to preventively diagnose a power transformer. But the criterion and algorithm of this item are not established yet in korea. In this paper, criterion and alarm level of the on-line dissolved gas analysis are based on the analysis of on-line data of operating transformers, Korea industrial standard and operation manual for a power transformer as well as accumulated data of the preventive diagnosis systems which have been operated at nine substations of Korea Electric Power Co.(KEPCO) since 1997, Therefore, the criterion and alarm level proposed in this paper are to be well suitable and are adaptable for the domestic operational environments and conditions of the power transformer. Considering that the conventional diagnosis system is capable only of accumulating and monitoring data of the power transformer operation, the criteria and the algorithms make it possible to accomplish an ultimate goal of the preventive diagnosis system. It is expected, therefore, that they will have a beneficial effect on broad applications of the preventive diagnosis system and the achievement of manless substation system in the future.

• 전력전자학회논문지
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• 제20권4호
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• pp.297-304
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• 2015

A conventional single-phase high-power system typically generates a large AC line input current at universal 90 VAC condition. Sometimes, this phenomenon can block the Earth Leakage Circuit Breaker (ELCB), which causes problems. Replacing power facilities is essential to ensure smooth operations. Thus, this paper proposes a method that can drive higher power than the limit of conventional power facilities. The proposed method can reduce the large AC line input current by limiting the input power of Power Factor Correction (PFC). An additional battery circuit can supplement the power deficiency. Specifically, a bidirectional converter with charging and discharging functions was adopted for the battery circuit. Finally, the validity of the proposed system could be confirmed by modal analysis and simulation, and an experiment in 2 KW condition was implemented with a prototype sample as well.