• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전기물성,응용부문
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• pp.151-159
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• 2003

According to the records, approximately 50 percent of power failure were caused by lightning. Conventional fault preventive measures against lightning include reduction of the footing resistance of the tower, multiplication of overhead ground wires and unbalanced insulation of the double circuit transmission tower. In addition to these, transmission line arresters have been recently appeared as an alternatives. In this paper an unbalanced insulation method with transmission line arrester was assumed as another countermeasure against simultaneous double circuit trip of 154 kV transmission line by lightning strike. The lightning performance of line arrester was compared with conventional insulation concept using different numbers of porcelain and glass insulator. Larger numbers of insulator simply increase flashover current level by lightning but the lightning performance doesn't proportional to it. EMTP simulation and predictive calculation of lightning failure rate were carried out to evaluate the performance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.208-211
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• 2003

The western route of KEPCO's 765 kV transmission line has been tentatively operating as 345 kV voltage before commercial operation. KEPCO decided to operate the 765 kV line for commercial operation after completing the test operation of 765 kV substation in 2002. In the process of energizing the line as 765 kV voltage, double circuit transmission line will be operated with two voltage grades of 765 kV and 345 kV. As the earthing switches are installed on both ends of the line, electrostatic induction voltage and electromagnetic induction current were calculated prior to the line energizing in order to confirm the ratings. The induced voltage and current are important for the maintenance of the parallel circuit. This paper presents the simulation results of electrical phenomena such as electrostatic induction voltage and electromagnetic induction current from the parallel line. The transmission line was modeled by EMTP (Electro-Magnetic Transient Program). The simulation results were compared with the measured results at the field.

• Journal of Electrical Engineering and Technology
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• 제12권3호
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• pp.1046-1052
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• 2017

The load on the power grid of South Korea is expected to grow continuously until the late 2020s, and it is necessary to increase the transfer capacity from the Eastern grid to the Seoul-Gyeonggi region by reinforcing the transmission network for the electric power system to remain stable. To this end, the grid reinforcement by two bipole LCC HVDC transmission systems have been considered on account of the public acceptability and high growth of the fault current level, even though an additional 765kV system construction is more economical. Since the probability of the existing 765kV double circuit transmission line trip is extremely low, a dynamic simulation study was carried out to estimate the efficient HVDC capacity able to stabilize the transient stability by utilizing the HVDC overload capability. This paper suggests the application plan to reduce the HVDC construction capacity with ensuring the transient stability during the 765kV line trip.

• 대한전기학회논문지:전력기술부문A
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• 제50권3호
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• pp.146-152
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• 2001

This paper describes an accurate fault location algorithm based on sequence current distribution factors for a double-circuit transmission system. The proposed method uses the voltage and current collected at only the local end of a single-circuit. This method is virtually independent of the fault resistance and the mutual coupling effect caused by the zero-sequence current of the adjacent parallel circuit and insensitive to the variation of source impedance. The fault distance is determined by solving the forth-order KVL(Kirchhoff's Voltage Law) based distance equation. The zero-sequence current of adjacent circuit is estimated by using a zero-sequence current distribution factor and the zero-sequence current of the self-circuit. Thousands of fault simulation by EMTP have proved the accuracy and effectiveness of the proposed algorithm.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권5호
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• pp.231-238
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• 2006

This paper analysed the induced current density inside human body of hot-line worker for 765kV double circuit transmission line according to locations of human body. Human model was composed of several organs and other parts, whose shapes were expressed by spheroids or cylinders. Organs such as the brain, heart, lungs, liver and intestines were taken into account. Applying the 3 dimensional boundary element method, we calculated induced current density in case a worker was located inside and outside a lowest phase of 765 kV transmission line in which a 60% current of maximum load flowed. As results of study, we found a maximum induced current density in all organs was less than $10mA/m^2$ when a wonder was outside. As one in brain and heart was higher than $10mA/m^2$ when a worker was inside, we propose a method for lowering current density.

• 전기학회논문지
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• 제61권3호
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• pp.373-379
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• 2012

This paper presents a fault location algorithm based on the adaptively estimated value of the local sequence source impedance for faults on a parallel transmission line. This algorithm uses only the local voltage and current signals of a faulted circuit. The remote current signals and the zero-sequence current of the healthy adjacent circuit are calculated by using the current distribution factors together with the local terminal currents of the faulted circuit. The current distribution factors consist of local equivalent source impedance and the others such as fault distance, line impedance and remote equivalent source impedance. It means that the values of the current distribution factors can change according to the operation condition of a power system. Consequently, the accuracy of the fault location algorithm is affected by the two values of equivalent source impedances, one is local source impedance and the other is remote source impedance. Nevertheless, only the local equivalent impedance can be estimated in this paper. A series of test results using EMTP simulation data show the effectiveness of the proposed algorithm. The proposed algorithm is valid for a double-circuit transmission line system where the equivalent source impedance changes continuously.

• 조명전기설비학회논문지
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• 제21권7호
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• pp.20-28
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• 2007

본 논문에서는 2회선 가공송전선에 대하여 2회선 중 1회선에 고장이 발생한 경우에 안전하게 운전할 수 있는 단시간정격을 결정하기 위한 해석적 방법을 기술한다. 도체의 온도특성을 나타내는 열평형방정식을 선형화 함으로써 이 선형방정식으로 1회선 선로에 과부하가 발생하는 동안 과전류와 그 온도 특성을 쉽게 표현할 수 있다. 일반적으로 단시간 선로정격은 도체의 수명과 이도를 동시에 고려하여 결정해야 한다는 것은 잘 알려진 사실이다. 그렇지만 대부분의 전력회사는 단시간정격에 대한 각자의 다른 지침을 갖고 있다. 이 논문에서는 제안된 방법을 사용하면 과거 3시기에 건설된 한국전력공사의 가공송전선에 규정된 단시간정격을 재평가할 수 있고, 그 결과 단시간정격을 효율적으로 증대시킬 수 있음을 확인하였다. 또한 이 방법은 2회선 선로 중 1회선에 고장이 발생할 경우에 기존 선로에 어떤 조치도 하지 않아도 단시간 동적송전용량을 결정하는데 직접 이용할 수 있을 것이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1509-1511
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• 1994

This paper calculates the induced voltage and current for a human and a car under 765 kV AC double circuit transmission line. A human and a car is simulated as two dimension by the use of charge simulation method and as three dimension by using surface charge method. The phase arrangement of transmission line is varied to calculate the induced voltage and current. In two cases a human and a car is grounded or floated, the induced voltage and current is also compared.

• 대한전기학회논문지:전력기술부문A
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• 제50권1호
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• pp.38-44
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• 2001

For double-circuit transmission line systems, an accurate digital distance relaying algorithm immune to the reactance effect is proposed. The apparent impedance calculated by the distance relay is influenced by the combined reactance effect of the fault resistance and the load current as well as the mutual coupling effect caused by the zero-sequence current of the adjacent parallel circuit. To compensate the magnitude and phase of the estimated impedance, this algorithm uses phase angle difference between the zero(positive) sequence of the both side of the system seperated by the fault point. The impedance measuring algorithm presented used a current distribution factor to compensate mutual coupling effect instead of the collected zero-sequence current of the adjacent parallel circuit.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권2호
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• pp.117-126
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• 1999

The environmental impact of the KEPCO 765-kV transmission line was studied using a full scale test line in order to develop the design technology. Therefore this paper describes an environmental design summary of the audible noise, hum noise, wind noise, radio interference, TV interference and electric field measurement from the KEPRI 765-kV double circuit transmission test line with a bundle of $6-480mm^2$ conductors per phase. The analysis of the test results shows that 6-Rail and 6-Cardinal conductors bundle satisfy the audible noise criterion & TV interference under the stable rainy weather condition and the radio interference level under the fair weather. And the other items are also agreed with the design level criterion for KEPCO 765-kV transmission line.