• Journal of Electrical Engineering and Technology
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• v.1 no.2
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• pp.161-169
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• 2006

Load representation has a significant impact on power system analysis and control results. In this paper, composite load models are developed based on on-line measurement data from a practical power system. Three types of static-dynamic load models are derived: general ZIP-induction motor model, Exponential-induction motor model and Z-induction motor model. For the dynamic induction motor model, two different third-order induction motor models are studied. The performances in modeling real and reactive power behaviors by composite load models are compared with other dynamic load models in terms of relative mismatch error. In addition, numerical consideration of ill-conditioned parameters is addressed based on trajectory sensitivity. Numerical studies indicate that the developed composite load models can accurately capture the dynamic behaviors of loads during disturbance.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.57-61
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• 2006

In the single-phase switched reluctance motor (SRM) drive, the required DC source is generally supplied by the circuit consisting of bridge rectifier and large filter capacitor connected with DC line terminal. Due to the large capacity of the capacitor, the charged time of capacitor is very short from the AC source. Lead to the bridge rectifiers draws pulsating current from the AC source side, which results in reduction of power factor and low system efficiency. Therefore a novel single-phase SRM drive system is presented in this paper, which includes drive circuit realizing reduction of torque ripple and improvement of power factor with a novel switching topology. The proposed drive circuit consists of one switching part and diode, which can separate the output of AC/DC rectifier from the large capacitor and supply power to SRM alternately, in order to realize the torque ripple reduction and power factor improvement through the switching scheme. In addition, the validity of the proposed method is tested by some simulations and experiments.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.121-124
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• 2003

In this paper, a novel PFC AC / DC converter is presented to be appropriate for AC PDP's power driving system. The conventional PFC AC / DC converter has independent power stages and controllers for their switching respectively, which should have increased price, size on manufacturing and decreased its efficiency as well. So this advanced Single-Stage Power Factor Corrector is presented and verified through spice simulation.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.177-181
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• 2003

Need of power stability, reliability is increased, as using of sensitive: nonlinear load are increasing. Therefore, Power Quality Problems become the center of public interest. Many kinds of algorithms have been studied for monitoring of Power Quality Problems. Monitoring algorithms of using RMS, FT and the others are easy to applicate to system. But, it is not enough to monitor all of Foyer. Quality problems. Wavelet Transform is more proper to applicate. so, This paper presents measurement system using discrete wavelet transform.

• Journal of Power System Engineering
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• v.7 no.1
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• pp.42-50
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• 2003

최근의 배전반 설비의 고성능, 안정성, 신뢰성은 전기에너지의 사회적 욕구로 요구되고 있다. 본 논문에서는 전력품질에 관한 정보를 수집하고 통합 모니터링과 설비의 보호, 그리고 다양한 장치들을 제어할 수 있는 전력 모니터링 시스템의 개발에 대하여 고려하고자 한다. 전력품질 모니터링을 통하여 수집된 정보는 시스템의 효과적인 운용과 사용상의 신뢰성을 개선시킨다. 본 시스템은 크게 하드웨어부와 소프트웨어부로 구성된다. 하드웨어부는 원칩 마이크로 프로세서(Intel 80C196KC)를 사용한 측정과 제어, 통신 그리고 입/출력을 담당하는 다기능 인디케이터와 컨트롤러로 구성된다. 다양한 기능의 모니터링, 데이터베이스와 제어를 PC상에서 구현하기 위한 소프트웨어부는 사용자 그래픽 인터페이스(GUI) 기반의 비주얼 프로그래밍을 사용하여 개발되었다.

• Journal of Power System Engineering
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• v.15 no.3
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• pp.12-17
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• 2011

Gears are useful for power transmission due to excellent power transmission performance, low cost, and compactness. In addition, gears have constant speed ratio, compact structure, and excellent efficiency. In order to transmit higher power, the new multi-range transmission requires gears which have greater strength than the existing transmission. This study evaluates stability and durability through gear analysis of the multi-range transmission in commercial vehicles using ROMAX-DESIGNER program. Also, strength design evaluation is carried out by the analysis results which are compared with gear strength theory of AGMA standard. Bending stress and contact stress on gears are lower than their allowable stresses. Therefore, we can evaluate the safety of the gear strength design in multi-range transmission.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1191-1192
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• 2011

We released new triple redundant digital excitation system with real time generator-turbine simulator. One of its great merits is the real time generator-turbine simulator when it was compared with the other products. If excitation system is tripped by unexpected faults, Maintenance man can do easily performance test of digital excitation control board, sequence relay and thyristor switching device of phase controlled rectifier without manufacturer's support. For the verification of this system, It was tested with an actual excitation system implemented on 5kVA M-G Set. After finishing the tests, the trial product will be installed and operated at a 500MW thermal power plant.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.208-211
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• 2003

This paper presents an improved droop method of the high voltage DC power supply which minimizes the voltage droop of a parallel-connected power supply. Conventionally, the droop method has been used to achieve a simple structure and no-interconnections among the power sources. However, it has a trade-off between output voltage regulation and load sharing accuracy. In this paper, the droop is minimized with a current and droop gain control using steady-stage estimation. The proposed method can achieve both high performance voltage regulation and load sharing. Two 10kV, 100mA parallel power modules were made and tested to verify the proposed current-sharing method.

• Journal of Power Electronics
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• v.8 no.1
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• pp.1-9
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• 2008

This paper presents the design and analysis of a new input AC current wave shaping AC-DC converter for cost effective harmonic mitigation under varying loads. The proposed converter consists of a delta-polygon connected autotransformer based twelve-pulse AC-DC converter and a small rating passive shunt filter tuned at $11^{th}$ harmonic frequency. The proposed AC-DC converter eliminates the most dominant $5^{th},\;7^{th}$ and $11^{th}$ harmonics and reduces higher order harmonics; thereby, resulting in an improved power quality at AC mains. Moreover, the design of the autotransformer is modified to make it suitable for retrofit applications, where presently a 6-pulse diode bridge rectifier is used. To validate the proposed approach, various power quality indices are presented under varying loads. Experimental results obtained on the developed converter are given to validate the model and design of the proposed converter.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.4
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• pp.149-158
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• 2018

With the propagation and spread of the new regeneration energy and increase in electricity demand, power systems tend to be decentralized, and accordingly, the use of a power system stabilizer tends to expand for the stabilization of the distribution system. Thus, typical power system stabilizer, Static Var Compensator (SVC) is developed on a variety of topologies. In addition, the trend of technology leads from SVC to Static Synchronous Compensator(STATCOM) technology development. Recently, to overcome STATCOM's conversion losses and economic disadvantages, studies of a hybrid method using STATCOM and SVC in parallel have actively been conducted. This study proposes a new Soft-Step Switching method to limit inrush current problematic in Thyristor Controlled Capacitor (TCC) method in SVC function. In addition, to reduce Statcom's capacity, groups of reactive power compensation reactor and condenser for SVC were designed.