• KEPCO Journal on Electric Power and Energy
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• v.2 no.2
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• pp.307-310
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• 2016

The operational cost for maintaining the superconductivity of high-temperature superconducting (HTS) cables needs to be reduced for feasible operation. It depends on factors such as AC loss and heat transfer from the outside. Effective operation requires design optimization and suitable operational conditions. Generally, it is known that critical currents increase and AC losses decrease as the operational temperature of liquid nitrogen ($LN_2$) is lowered. However, the cryo-cooler consumes more power to lower the temperature. To determine the effective operational temperature of the HTS cable while considering the critical current and AC loss, critical currents of the HTS cable conductor were measured under various temperature conditions using sub-cooled $LN_2$ by Stirling cryo-cooler. Next, AC losses were measured under the same conditions and their variations were analyzed. We used the results to select suitable operating conditions while considering the cryo-cooler's power consumption. We then recommended the effective operating temperature for the HTS cable system installed in an actual power grid in KEPCO's 154/22.9 kV transformer substation.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.3
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• pp.271-278
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• 2020

KEPCO Research Institute developed a GIS-based autopilot drone inspection system for electric power facilities and since its pilot application in 2017, it has been successfully used to detect defects in power transmission lines. This paper presents how to operate this system in the field of power line inspection. Power transmission lines are located in a wide variety of environments such as plains, mountains, river crossings, sea crossings, and industrial areas. Among these, some transmission lines are difficult for human workers to access because of their geographies and some should be checked more often due to their severe contamination. Considering these field conditions, we classified drone operation in two categories to increase its effectiveness and efficiency - patrol surveillance and detailed inspection tasks. This paper describes the detailed procedures of the two tasks above and their field application experiences. In addition, this paper newly proposes how to construct public drone roads by using the information of KEPCO's power transmission lines.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1822-1823
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• 2011

If one system were retrofited in complexed several systems, the system has closely analyzed in its function. And, so the system is operating stable after retrofit. Especially, the system is analyzed considerate in not retrofitting totally but retrofitting partially. Now, generator excitation system will be retrofitted partially(that is, retrofitting controller) and the contents is described in this paper.

• KEPCO Journal on Electric Power and Energy
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• v.1 no.1
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• pp.1-8
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• 2015

When the line and switchgear of the substation system are disconnected, ferro-resonance can occur. This happens even if the capacitive reactance and inductive reactance are not equal, which are not common resonance conditions. Resonance conditions vary depending on the busbar configuration environment. Although the damping resistance method applying the existing saturable reactor to cope with ferro-resonance has been successfully applied on site, there can be loss of normal function during long-term operation. The reason is because the rise in the operating frequency of saturable reactors means the saturation number is increased. Therefore, it can no longer function as saturable reactor since the resistor having inadequate capacity is burned out. To address this problem, in this paper, an EMTP-based simulation test was performed by designing and applying a dual reactor method, which adds an extended divergence reactor to the 1st side of the VT. The test result confirms that when the divergence reactor is inserted, the voltage and current values obtained at the 1st side and 2nd side of the VT as well as current values of divergence reactor part were stabilized from the transient phenomena and return to normal values. When compared with existing measures, although this method is similar in adding having a reactor added to a system regarding ferro-resonance, it has the advantage of being able to prevent ferro-resonance in advance since the reactor is added before the system is saturated. In addition, because it does not use damping resistance, it can extend the equipment life and stabilize its operation. Therefore, there are a lot of differences in terms of its operating characteristics and achivement of goal between the conventional method and new divergence reactor method.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2007.11a
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• pp.112-119
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• 2007

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.10
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• pp.1681-1687
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• 2008

This paper shows application of optimal reconfiguration algorithm for distributing power system to KEPCO system for loss minimization and load balancing. That is, it suggests additional algorithm to check potential problems caused in case of theoretical algorithm being applied to real system and recover from them. Also, comparing the results of reconfiguration algorithm Tabu-Search Algorithm applied to current KEPCO distribution power system and those of Branch Exchange Algorithm using initial operation point suggested in this paper, it shows how much the results are improved in aspects of load balancing, loss reduction and calculating time.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.205-207
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• 1993

Distribution planning requires comprehensive knowledge about not only distribution but also transmission/subtransmission system expansion plan. At the same time, distribution planning is very time consuming and a series of routine job which involves a lot of experience and efforts of planning engineers. Since the quality of distribution planning depends upon the ability of planning engineers, the economy of investment should be taken into consideration. The object of this study is to establish a computerized distribution planning system which helps distribution engineers finding a new system expansion plan. It provides the engineers with at optimal system expansion plan which satisfies the condition of both reliability and economy.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.344-345
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• 2011

A necessity to a superconducting cable in power transmission systems have been growing more and more due to high power density in urban areas and rapid increase of power demand. In view of these situation, it is a noteworthy fact that superconducting cable has remarkable advantages, such as lower power loss and 3-5 times higher power transmission capacity, compared with conventional power cable. For the last a few years, long-term reliability tests had been carried out in the KEPCO PT Center, and now it has been installed in KEPCO's real power grid for demonstrating commercial operation. This paper deals with the test results of dielectric properties performed at manufacturing factory for the joint box, termination and core of HTS cable system and whole system connected in real power grid.

• New & Renewable Energy
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• v.2 no.3
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• pp.15-22
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• 2006

As the distributed generation becomes more reliable and economically feasible, it is expected that a higher application of the distributed generation units would be interconnected to the existing grids. This new market penetration using the distributed generation technology is linked to a large number of factors like economics and performance, safety and reliability, market regulations, environmental issues, or grid connection standards. KEPCO, a government company in Korea, has performed the project to identify and evaluate the performance of Micro Gas Turbine(MGT) technologies focused on 30, 60kW-class grid-connected optimization and combined Heat & Power performance. This paper describes the results for the mechanical, electrical, and environmental tests of MGT on actual grid-connection under Korean regulations. As one of the achievements, the simulation model of Exhaust-gas Absorption Chiller was developed, so that it will be able to analyze or propose new distributed generation system using MGT. In addition, KEPCO carried out the field testing of the MGT Cogeneration system at the R&D Center Building, KEPCO. The field test was conducted in order to respond to a wide variety of needs for heat recovery and utilization. The suggested method and experience for the evaluation of the distributed generation will be used for the introduction of other distributed generation technologies into the grid in the future.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1197-1198
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• 2011

발전기 여자시스템(Excitation System)은 동기발전기의 계자권선에 직류전류를 공급하고 계자전압을 조정하여 발전기의 전압 및 계통의 무효전력을 제어하는 기능을 수행한다. 본 논문에서는 발전기 여자시스템의 모델링 기법과 현장 운전데이터를 이용한 여자시스템의 모델링 결과들을 기술하였다.