• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.7
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• pp.352-357
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• 2005

In competitive electricity markets, the System Operator (SO) coordinates the overall maintenance schedules when the collective maintenance schedule reported to 50 by Gencos not satisfy the specified operating criteria, such as system reliability or supply adequacy. This paper presented a method that divides generator maintenance scheduling of the 50 into a master-problem and a sub-problem. Master-problem is schedule coordination and sub-problem is DC-optimal power flow. If sub-problem is infeasible, we use the algorithm of modifying operating criteria of master-problem. And, the 50 should use the open information only, because the information such as cost function of a generator and bidding Price is highly crucial for the strategies of profit maximization.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.798-800
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• 2005

In competitive electricity markets, the System Operator (SO) coordinates the overall maintenance schedules whenever the collective maintenance schedule reported to SO by Gencos & Transco in the pool does not satisfy the specified operating criteria, such as system reliability or supply adequacy. We propose a two-layer mathematical algorithm amenable to maintenance scheduling problem into master problem and sub-problem. The master problem coordinates the scheduling, and sub-problem, DC optimal power flew, checks the adequacy. The proposed algorithm was demonstrated with a case study.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.10
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• pp.542-549
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• 2004

The conventional fault location algorithms based on the travelling waves have an inherent problem. In cases of the close-up faults occurring near the relaying point and of the faults having zero degree inception angle of voltage signals, the conventional algorithms can not estimate an accurate fault distance. It is because the shapes of travelling waves are near sinusoidal in those cases. A new method solving this problem is presented in this paper. An FIR(Finite Impulse response) filter which makes high frequency components prominent and makes the power frequency component and dc-offset attenuated is used. With this method, the cross-correlation peak is to be very clear when a close-up fault or a fault having near zero-degree inception angle occurs. The cross-correlation peaks can be clearly distinguished and accurate fault location is practically possible consequently. A series of simulation studies using EMTP(Electromagnetic Transients Program) show that the proposed algorithm can calculate an accurate fault distance having maximum 2% or less error.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.7
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• pp.397-404
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• 2004

This paper describes a study of transient characteristics in 765kV untransposed transmission lines. As the 765(kV) system can carry bulk power, some severe fault on the system nay cause large system disturbance. The large shunt capacitance and small resistance of 765kv transmission line make various difficulties for its protection. These problems including current difference between sending and receiving terminals on normal power flow, low order harmonic current component in fault current and current transformer saturation due to the long DC time constant of the circuit etc. must be investigated and solved. The analysis of transient characteristics at sending terminal has been carried out for the single phase to ground fault and 3-phase short fault, etc. The load current, charging current in normal condition and line flows, fault current, THD(Total Harmonic Distortion) of harmonics, time constants have been analysed for the 765kV untransposed transmission line systems.

• Proceedings of the KIEE Conference
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• summer
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• pp.409-411
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• 2004

The need for Fault Current Limiters (FCL) is associated with the continuous growth and interconnection of modem power systems and increase in dispersed generation facilities, which result in progressive increase in the short circuit capacity far beyond their original design capacity. Fault Current Limiters (FCL) clips the fault currents and reduces the electromechanical stresses on the network and the need to handle excessive fault currents. In addition, the reduction of the fault duration Provided by the limiter should increase the power transmission capability and improve the dynamic stability. This paper proposes the model of resistive type superconducting fault current limiter using EMTDC(Electromagnetic transients for DC analysis program). In order to verify the effectiveness of the SFCL, in this paper, the analysis of fault current in a transmission system through the EMTDC based simulation by using the modeled component of a resistive type SFCL is peformed and the detailed results are given.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.1
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• pp.1-8
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• 2016

The characteristics of Korean power systems are large capacity of generation sites and concentrated load in Seoul metropolitan area. According to the national generation facility plan, more generation facilities are needed to be constructed as the electrical demands are forecasted to increase. Moreover, the size of generation sites are expected to increase, too. Therefore transient stability problems become worse and worse. Recently, the necessity of HVDC has been raised to overcome the difficulty of constructing HVAC transmission lines. This paper shows the analysis of transient stability when HVDC transmission system is added to the power system consisting of large generation sites.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.25-26
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• 2008

A, B 변전소간에 345kV 지중선로 4회선으로 Loop 운전 중 1개의 지중선로에 절연파괴 고장이 발생하였으며, 이때 4개의 지중송전선로가 모두 운전정지 되는 고장이 발생하였다. 고장이 발생한 선로는 정상적으로 보호계전기가 동작하였으나, 그 외 다른 선로의 보호계전기가 오동작하여 원인규명시험을 한 결과 외부고장시 CT 포화로 인해 보호계전기가 자단고장으로 인식하여 동작된 것으로 분석되었다. 본 논문에서는 CT 포화와 관련하여 DC성분, Surge, 2차 부담 등 여러가지 조건에 대하여 고찰함으로서 향후 전력계통의 다양한 고장에 대비하는데 도움이 되기를 기대한다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.547-548
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• 2015

In order to reduce error of the distance relay, we propose an improved fault locating scheme using DC offset removal filter. We were modeled 154 kV transmission system using ATP software in order to demonstrate the usefulness of proposed scheme, and applied to the proposed scheme using collected voltage signal and current signal by line-to-ground fault.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.447-454
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• 1998

This paper describes a modeling and current control techniques of Distribution static condenser (D-STATCON) for power factor compensation. The current control is based on the predictive and the space vector PWM scheme. The predictive current controlled PWM D-STATCON can maintain its performance with power factor compensation and fixed switching frequency. By using the space vector control low ripple and offset in the current and the voltage as well as fast dynamic responses are achieved with a small DC link capacitance employed.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.395-397
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• 1999

This paper presents a method of improving the power factor and the waveform of A.C line currents and the out waveforms of AC to DC fully bridge converter systems which is achieved by connecting converters in series and parallel. The results of simulation show that the power factor and the source voltage and current waveforms are improved by the method of connecting converter in series, and the controlled input voltage and current waveform using a current limit controller.