• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.852-854
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• 1988

An expert system is developed to solve the voltage problems occurring in electric transmission power system. It is based on knewledge engineering technique satisfies the performance criteria such as minimizing the number of operation of control device and quantity of reactive power. Also, it uses best-first search technique from the experts. Control devices used in this paper include shunt capaciter/reactor, transformer tap changer, generator output voltage and a generator is used after the availability of other two devices are checked.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.214-215
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• 1994

The VCB(Vacuum Circuit Breaker), which has been used in power distribution system, have prevented the performance of the phase modifying equipment (Condenser Bank and Shunt Reactor) and the important parts in the electric power system because of the transient voltage in opening and closing circuit. So, we developed the 25.8kV $SF_6$ gas GCB(GAS Circuit Breaker), which had the few occurance of the surge in opening & closing circuit and had the high reliability, based in our own technology.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1187-1193
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• 2010

This paper provides the methods for enhancing the stability with normal or emergency operating conditions in real power systems and copes with the unbalance of demand of reactive power due to the loss of facility, such as 765kV transmission line. In this paper, we focused on the maximum allowable transmission power(hereafter, MAXTP) in the metropolitan area. In order to increase the MAXTP, the application of reactive power compensators, SVC, and Shunt compensator and reactor, is analyzed as an enhancing method of stability and MAXTP. Particularly, the f-V analysis was performed for the postulated contingency, in order to evaluate the effects on SVC. Conclusively, the stability of power systems could be enhanced and the MAXTP is increased effectively with Dongseoul SVC which has the capacity 200MVAr.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.571-573
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• 1995

This paper presents a method for optimal dispatch which minimizes transmission losses and improves voltage profile of power systems using genetic algorithm based on the mechanism of natural genetics and natural selection. The constraints are VAR sources(transformer tap, generator voltage magnitude and shunt capacitor/reactor), load bus voltages and generator reactive power. Real variable-based genetic algorithms which can save coding times and maintain the accuracy are applied for optimal dispatch of reactive power. The genes of genetic algorithm consisted of integers for considering discrete VAR sources. A efficient operator for crossover is proposed to consider the effect of close genes. The algorithm proposed can apply to problems for large scale power systems with multi-variables and complex nonlinear functions efficiently. The proposed method is applied to IEEE 30 buses model system to show its effectiveness.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.4
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• pp.201-206
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• 2003

Power system is analyzed by three methods of load flow, fault calculation, and voltage stability. Among there, load flow is calculated to flow of power in power in system at steady state. But, load flow is difficult to analyze to flow of power in substation, because power flow frequently alter by various equipments such as circuit bleaker, disconnect switch and shunt reactor. Particular, in 765[㎸] system, because of form of 1.5GB for stable operation, structure of substation has been very complex. In this paper, we describe technique for application of load flow algorithm in simulator for 765[㎸] substation. For this technique, we built each database for various equipments and considered form of 1.5GB Data as form of bus and line, for application of load flow, are acquired from built database, and then calculate load flow in substation. And. results of load flow are outputted in screen of operator console program.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.3
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• pp.115-123
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• 1985

A two phase chopper system with two separate groups of DC motors for regenerative braking is dealt with in this article. The main circuit consists of two sets of chopping parts, four diodes and two separate groups of DC motors. Although the proposed chopper circuit requires more circuit elements than the conventional two phase chopper system with combined output, it has the following advantages`(1). Ripple frequency of smoothing reactor current becomes twice as high as that of the conventional system, so the continuous current range and the ripple ratio are improved greatly. Therefore, the efficiency becomes even higher, the capacity of commutation equipment is reduced and the inductive interference become less.(2). Load current division becomes equalized. Therefore it is possible to drive not only series motors but also shunt, separately excited and compound motors.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.764-767
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• 1996

Design & operation of power system for meeting increase of electric power demands is becoming more difficult and complex. One of reasons is increase of fault current. As one of the most effective methods for suppressing the fault currents, installation of SFCL are expected. An image of future hybrid & total SC power system which have introduced SC generator cable transformer, fault current limiter, SMES & shunt reactor, etc. are presented. In the SC power system, it is pointed that a SFCL should play an, important part of quenching current level coordination to prevent the other SC devices from quench.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.471-472
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• 2007

현재 다양한 전압보상설비들이 전력계통에 적용됨에 따라 각 기기의 특성을 이용한 설비간 상호 작용을 통해 전력공급의 유연성을 확보하고 설비들의 효율적인 활용이 요구된다. 따라서 본 논문에서는 전압보상설비들[UPFC(Unified Power Flow Controller Shunt elements(Sh. Capacitor & Sh. Reactor) ULTC(Under Load Tap Changing)] 간의 협조제어 모델링 및 시뮬레이션을 통해 각 부하모선별전압 요구치를 만족하도록 계통의 전압을 제어 및 유지하는 방안을 제안하였다. 이는 기기의 성능향상과 급변하는 전력계통 상황에 능동적인 대처가 가능할 것으로 기대되고, 수용가에 양질의 전력 공급이 가능하게 될 것이다.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1041-1043
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• 2005

It is expected to reduce stresses to components of high voltage circuit breaker and transferred switching surge from power system by applying controlled switching technique to high voltage system. This technique has already been applied to switch shunt reactor or capacitor bank in advanced countries. In this paper, operating software is installed in developed controlled switching device and HMI(Human-machine Interface) is under developing, In the future, this technique is expected to contribute to S.A(Substation Automation).

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.198-200
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• 2004

The purpose of this paper is to explain improvement of voltage stability using STATCOM by active power margin and reactive power margin. STATCOM, the representative shunt compensator of the FACTS devices, is faster than machinery compensator in response speed and has the advantage of the small scale because it doesn't use reactor or large capacitor. In this paper, we investigated the compensatory effect of the STATCOM that applied to KEPCO system.