• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.7
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• pp.854-859
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• 2018

This paper describes the characteristics of a hybrid supercapacitor module for power quality stabilization. Hybrid supercapacitor is an promising energy storage device that positioned between conventional EDLC and Li-ion battery. A cylindrical 7500F hybrid supercapacitor ($60{\times}138mm$) was assembled by using the $Li_4Ti_5O_{12}$ electrode as an anode and activated carbon as a cathode. Considering the ESR and efficiency has been designed to module with 41.6F 480V design results in 180 series combination. In order to determine the characteristics of the hybrid supercapacitor module for power system, hybrid supercapacitor cells were connected in series with active balancing circuit. As a result of measuring the 50kw UPS, it was discharged at the current of 104A~143A during the discharge in the voltage range of 350V~480V, and the compensation time at discharge was measured to be about 30s. These results can be used to stabilization of power quality by applying hybrid supercapacitor module.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.5
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• pp.453-459
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• 1991

This paper presents a new algorithm to select optimal parameters and location of power system stabilizer (PSS). A new performance measure, which evaluates the share of a particular mode among state responses, is introduced. The gradient of the performance measure with respect to PSS parametes is derived in an explicit form, so optimal parameters of PSS can be obtained by the steepest descent method. The machine, with which it is most probable to reduce the performance measure, is identified as the optimum site for PSS application.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.967-969
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• 1998

In this paper, the proposed controller is obtained by combining the nonlinear feedback linearization-sliding mode controller (NFL-SMC) with the full order observer (FOO) and eliminates the need to measure all the state variables in the conventional NFL-SMC.

• Journal of Electrical Engineering and Technology
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• v.7 no.5
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• pp.664-671
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• 2012

This paper presents the application of Unified Power Flow Controller (UPFC) in order to simultaneous control of power flow and voltage and also damping of Low Frequency Oscillations (LFO) at a Single-Machine Infinite-Bus (SMIB) power system installed with UPFC. PI type controllers are commonly used controllers for UPFC control. But for the sake of some drawbacks of PI type controllers, the scope for finding a better control scheme still remains. In this regard, in this paper the new IP type controllers are considered as UPFC controllers. The parameters of these IP type controllers are tuned using Genetic Algorithms (GA). Also a stabilizer supplementary controller based UPFC is considered for increasing power system damping. To show the ability of IP controllers, this controller is compared with classical PI type controllers. Simulation results emphasis on the better performance of IP controller in comparison with PI controller.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.2
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• pp.175-181
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• 2009

In this paper, it is suggested that the selection method of parameter of Power System Stabilizer(PSS) with robustness in low frequency oscillation for Static VAR Compensator(SVC) using a self tuning fuzzy controller for a synchronous generator excitation and SVC system. The proposed parameter self tuning algorithm of fuzzy controller is based on the steepest decent method using two direction vectors which make error between inference values of fuzzy controller and output values of the specially selected PSS reduce steepestly. Using input-output data pair obtained from PSS, the parameters in antecedent part and in consequent part of fuzzy inference rules are learned and tuned automatically using the proposed steepest decent method.

• Journal of Power System Engineering
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• v.4 no.2
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• pp.31-39
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• 2000

Relationships between the plating condition and the plating rate of the deposition film for the electroless plating of Co-Cu-P alloy were discussed in this report. The result obtained from this experiment were summarized as follow ; The optimum bath composition was consisted of 0.8 ppm thiourea as a stabilizing agent. Composition of the deposit was found to be uniform after two hours of electroless plating. Plating rates of nickel-catalytic surface and zincate-catalytic surface were found to be very closely equal, but the plating time of nickel-catalytic surface took longer than that of the zincated-catalytic surface.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.754-756
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• 1998

In this paper the control methods for the synchronous generator is designed based on the two-degree-of-freedom (TDOF) control methods which can safisty the command following property and Robust control property at the same time. The power systems is reduced to one machine infinite-bus system. Robust stability of the proposed power system stabilizer is checked through the simulation considering the circumstance which can happen in real situation.

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.194-197
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• 2004

본 논문에서는 송전 계통사고 시 부하차단 이후 우리나라 2005년 계통에 대하여 전력계통안정화장치(Power System Stabilizer : PSS)의 영향 및 효과를 캐나다 Powertech Labs Inc.,의 TSAT(Transient Security Assesment Tool)을 이용하여 분석하였다. 모의를 위한 송전선로의 사고는 765kV 선로와 345kV 선로를 대상으로 하였으며, 8개의 모선에 대하여 상정 사고를 발생시켜 선로 차단 및 재투입을 고려하여 실시하였다. 본 연구에서 TSAT에 대한 기존의 전통적인 형태인 IEEEST type과 보다 정교한 이중구조를 가진 PSS2A type의 두 가지를 검토한 결과를 살펴보면 절반의 경우가 발전단 인근 지점의 사고시 발전기가 안정을 회복하지 못하고 탈조하는 것으로 나타났다. 그 외의 지역의 모선 단의 PSS투입효과는 비교적 댐핑 효과가 있는 것으로 나타났다.

• Proceedings of the KIEE Conference
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• 2002.04a
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• pp.228-230
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• 2002

Recently, electric power reliability of our country has been improved. However, there are still remaining problems which are short-duration variations like instantaneous and momentary interruption and voltage sag by nature calamity ; typhoon, lightning, snow, etc. Besides, power quality ; harmonics, caused by using power electronics equipments, become a hot issue Malfunction of controller and stop machinery, and losing the important data are caused by poor power quality at a couple of second. Due to those, UPS, which is made up battery, has being used, but there are several disadvantages ; long charge and discharge time, environmental problem by acid and heavy metal, and short life time. As generally know, micro-SMES is a method to settle those mentioned. However, there need huge system apparatuses in order to verify the effect of system efficiency and stability considering the size of micro-SMES, the sort of converter type, and various conditions ; inner temperature, magnetic field, quench characteristic of micro-SMES, and etc. In this paper, in order to bring the mentioned above to a settlement, a micro-SMES is modeled with characteristics of micro-SMES is interfaced to EMTOC program using Fortran program interface method. We obtained hopeful answers and made the simulation model of micro SMES.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.7
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• pp.350-358
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• 2000

Based on the results in the first-part paper, PSS tuning methods including the determination of PSS gain and compensation of phasor lagging are investigated in this second part. In the phase compensation, PSS should compensate phase lagging, resulted from power system-generator-excitation system loop, to provide damping torque in equal phase with the generator speed. Also, PSS gain should be determined to provide maximum damping torque as much as possible without the other modes unstable. In this paper, gain tuning method using the root-locus and the phase compensation of PSS at the one machine with infinite bus system are presented. The differences between PSS tuning at the tuning condition and at the least-stable condition are also discussed.