• 대한전자공학회논문지
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• 제12권2호
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• pp.28-30
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• 1975

2선식-4선식 접속을 위한 새로운 회로구성을 제안하였다. 이 회로구성은 현재까지 알려져 있는 회로구성과는 달라 전화기잡음방지회로 뿐만 아니라, 전화전송계의 임의의 중계장치에 이용될 수 있다. 이것은 또 IC화한 형태로 실현될 수 있다. In this paper a new network configuration for two-line four-line connection in telephone transmission system is proposed. It is proved that this network configuration is useful not only in an anti-sidatone circuit for telephone substation but also in a repeater station in the telephone system. It can ba realized in an integrated circuit.

• Journal of Electrical Engineering and Technology
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• 제5권2호
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• pp.191-196
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• 2010

Power system restoration following a massive or complete blackout starts with energizing the primary restorative transmission system. During this primary restoration process, unexpected overvoltage may happen due to nonlinear interaction between the unloaded transformer and the transmission system. In the case of the Myanmar electric power system, there are so many wide outage experiences, including complete blackout cases, caused by 230kV line faults and so on. Consequently, Myanmar's system operators have been well trained to deal with wide blackouts. Howver, system blackout restoration has been conducted by relying on the experience of only a few specialists. So, more scientific analysis is required to meet the requirements necessary to ensure fast and reliable system restoration. This paper presents analytical results on the primary restorative transmission system of Myanmar, focusing on the problems during the early restoration process. Methodologies are presented that handle load pick-up, terminal voltage and the reactive capability limitation of black-start generators to compensate the Ferranti effect. Static and dynamic simulation with the PSSolution and EMTDC programs respectively for the six cases are performed in order to select the primary restorative transmission lines.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.586-593
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• 2017

Modeling busbar distribution system as a transmission line is an important subject of power line communication in the smart grid concept. This requires extraction of busbar RLGC parameters, accurately. In this study, a comparison is made between conventional and modified method for the aspect of optimum RLGC parameters extraction in the 1 MHz to 50 MHz frequency band. The usefulness of these methods is shown both in time and frequency-domain analysis. The frequency-domain analyzes show that the inherent power of modified method can eliminate the errors especially due to the discontinuities arise in conventional method. This makes the modeling approach of modified method more advantageous for the busbars due to its robustness against disturbances in the S-parameters measurements which cannot be eliminated with the calibration procedure. On the other hand, time-domain simulations show that the transmission line representation of the modified method is closer to physical reality by handling causality issues.

• Journal of Electrical Engineering and Technology
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• 제8권3호
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• pp.428-435
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• 2013

Flexible AC Transmission System (FACTS) application study on enhancing the flexibility of AC power system has continued to make progress. A thyristor-controlled series capacitor (TCSC) is a useful FACTS device that can control the power flow by adjusting line impedances and minimize the loss of power flow and voltage drop in a transmission system by adjusting line impedances. Reduced power flow loss leads to increased loadability, low system loss, and improved stability of the power system. This study proposes the optimal location and compensation rate method for TCSCs, by considering both the power system loss and voltage drop of transmission systems. The proposed method applies a multi-objective function consisting of a minimizing function for power flow loss and voltage drop. The effectiveness of the proposed method is demonstrated using IEEE 14- and a 30-bus system.

• 대한전기학회논문지:전력기술부문A
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• 제49권8호
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• pp.412-417
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• 2000

TV ghost interference can be described as passive interference by the conducting part of transmission lines. In order to survey this interference from large-sized overhead EHV (extra high voltage) transmission line, TV reception quality was measured in the vicinity of that before and after construction. Instrumentation system was composed of ghost analyzer, TV received field intensity meter, VHF/UHF antennas, TV monitor and so on. The system is installed inside the vehicle. TV field intensity and PDUR (Perceived Desired wave to Undersired wave Ratio) are measured to evaluate TV ghost by using the system and vehicle. As the results, the useful data, which can be used to evaluate the effect of TV ghost interference from transmission lines could be obtained. In this paper, it is shown that the range of TV ghost interference from transmission lines can vary according to the frequency of TV electromagnetic wave, an incidence angle to the line and the other conditiions. At present, we are making efforts to establish a PDUR guideline for transmission lines.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.994-999
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• 1993

To service with high quality electricity to customer, the utilities consider the DAS (Distribution Automation System) as a good means of it. The backbone of the DAS are communication and computer technique. Most of all, from the economical and functional point of view, the selection of transmission media for system communication is the key factor to achieve a successful DAS. In this paper author propose the method of the DAS communication which share its channel with CATV transmission line and analyze the effect.

• Wind and Structures
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• 제34권2호
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• pp.215-230
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• 2022

Majority of transmission line system failures at many locations worldwide have been caused by severe localized wind events in the form of tornadoes and downbursts. This study evaluates the structural response of two different transmission line systems under equivalent F2 tornadoes obtained from real incidents. Two multi-span self-supported transmission line systems are considered in the study. Nonlinear three-dimensional finite element models are developed for both systems. The finite element models simulate six spans and five towers. Computational Fluid Dynamics (CFD) simulations are used to develop the tornado wind fields. Using a proper scaling method for geometry and velocity, full-scale tornado flow fields for the Stockton, KS, 2005 and Goshen County WY, 2009 are developed and considered together with a previously developed tornado wind field. The tornado wind profiles are obtained in terms of tangential, radial, and axial velocities. The simulated tornadoes are then normalized to the maximum velocity value for F2 tornadoes in order to compare the effect of different tornadoes having an equal magnitude. The tornado wind fields are incorporated into a three-dimensional finite element model. By varying the location of the tornado relative to the transmission line systems, base shears of the tower of interest and peak internal forces in the tower members are evaluated. Sensitivity analysis is conducted to assess the variation of the structural behaviour of the studied transmission lines associated with the location of the tornado relative to the tower of interest. The tornado-induced forces in both lines due to the three different normalized tornadoes are compared with corresponding values evaluated using the simplified load case method recently incorporated in the ASCE-74 (2020) guidelines, which was previously developed based on the research conducted at Western University.

• 한국전자파학회논문지
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• 제17권4호
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• pp.380-386
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• 2006

CPW(Co-Planer Waveguide) 전송선을 이용하여 자동차 연료 게이지 시스템인 전자식 연료 센더를 개발 제작하였다. 전송선 주위의 물질에 따라 전송선의 특성 임피던스가 변화되는 특성을 이용하였다. 자동차 연료통 속의 휘발유 혹은 경유의 높이에 따라 전송선의 특성 임피던스가 변화하면 반사량이 달라지므로 반사된 전압을 증폭함으로써 기존의 기계식 장치를 대체하는 시스템을 제작하였다. 브이(buoy)에 의한 부력과 연동된 저항 변화를 이용한 기존의 floating 방식이 갖는 기계식 작동 고장을 없애고, 유량 높이 오차를 줄이도록 하였다. 두께 1.6 mm의 Epoxy 기판에 CPW 전송 선로 및 제반 전자 장치를 구성하여 실측한 결과 기존 시스템에 비해 높이 오차가 적고 선형성이 우수한 특성을 보였다. 이 시스템은 PCB상 SMT로 제작되어 저가이면서도 양산성이 좋고 수명이 반영구적이어서 기존 시스템과의 경쟁력에서 우위를 보일 것으로 예상된다.

• Wind and Structures
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• 제13권5호
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• pp.451-469
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• 2010

The majority of weather-related failures of transmission line structures that have occurred in the past have been attributed to high intensity localized wind events, in the form of tornadoes and downbursts. A numerical scheme is developed in the current study to assess the performance of transmission lines under tornado wind load events. The tornado wind field is based on a model scale Computational Fluid Dynamic (CFD) analysis that was conducted and validated in a previous study. Using field measurements and code specifications, the CFD model data is used to estimate the wind fields for F4 and F2 full scale tornadoes. The wind forces associated with these tornado fields are evaluated and later incorporated into a nonlinear finite element three-dimensional model for the transmission line system, which includes a simulation for the towers and the conductors. A comparison is carried between the forces in the members resulting from the tornadoes, and those obtained using the conventional design wind loads. The study reveals the importance of considering tornadoes when designing transmission line structures.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1731-1733
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• 1997

The first 150lkV underground transmission line of Korea was installed between Danginri and Yongsan substation in 1974. Since then, the underground transmission lines of about 720 circuit-km had been installed up to 1995. As the national economy has been enlarged and the population of city has been rapidly increased, the demand of an electric power has been very increased. Therefore the first 345kV long-length transmission line of Korea was installed between Mikyum and Sungdong substation on Jan., 1997. This paper describes the design of the 345kV oil-filled cable and its accessories, the design of the system, the methods of installation, field tests, and the future trends of the underground transmission line in Korea.