• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.1361-1363
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• 2002

Micro-SMES(Superconducting Magnetic Energy Storage) has been studied as an impulsive high power supply for industrial applications. 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, goes down because of using power electronics equipments. Malfunction of controller and stop machinery, and losing important data are caused by poor power quality at a couple of second in accuracy controllers. Due to those, battery based UPS has been used, but there are several disadvantages ; long charge and discharge time, environmental problem by acid and heavy metal, and short life time. Micro-SMES is an alternative to settle problems mentioned above. 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. This paper presents a cost effective simulation method of micro-SMES and power converter, and design for micro-SMES based system using PSCAD/EMTDC.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기물성,응용부문
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• pp.96-99
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• 2001

In this paper, we present the simulation results of the multi-layer VCO(Voltage Controlled Oscillator), which is composed of the resonator, the oscillator and the buffer circuit. using EM simulator and nonlinear RF circuit simulator. EM simulator is used for obtaining the EM(Electromagnetic) characteristics of the conductor pattern as well as designing the multi-layer VCO. Obtained EM characteristics were used as real components in nonlinear RF circuit simulation. Finally the overall VCO was simulated using the nonlinear RF circuit simulator. The material for the circuit pattern was Ag and the dielectric was DuPont 951AT, which will be applied for LTCC process. The structure is constructed with 4 conducting layer. Simulated results showed that the output level was about 4.5[dBm], the phase noise was -104[dBc/Hz] at 30[kHz] offset frequency, the harmonics -8dBc, and the control voltage sensitivity of 30[MHz/V] with a DC current consumption of 9.5[mA]. The size of VCO is $6{\times}9{\times}2mm$(0.11[cc]).

• 한국전기전자재료학회논문지
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• 제15권6호
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• pp.492-498
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• 2002

In this paper, we present the simulation results of multi-layer VCO(voltage controlled oscillator), which is composed of resonator, oscillator, and buffer circuit, using EM simulator and nonlinear RF circuit simulator. EM simulator is used for obtaining the EM(Electromagnetic) characteristics of conductor pattern as well as designing the multi-layer VCO. Obtained EM characteristics were used as real components in nonlinear RF circuit simulation. Finally the overall VCO was simulated by the nonlinear RF circuit simulator. The material for the circuit pattern was Ag and the dielectric was Dupont 951AT, which will be applied for LTCC process. The structure of multi-layer VCO is constructed with 4 conducting layer. Simulated results showed that the output level was about 4.5 [dBm], the phase noise was -104 [dBc/Hz] at 30 [kHz] offset frequency, the harmonics -8 dBc, and the control voltage sensitivity of 30 [MHz/V] with a DC current consumption of 9.5 [mA]. The size of VCO is $6{\times}9{\times}2 mm$(0.11 [cc]).

• 전력전자학회논문지
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• 제6권6호
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• pp.525-537
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• 2001

본 연구에서는 펄스의 위치를 랜덤하게 함으로써 효율적은 RPWN (Random PWM)을 구현할 수 있는 새로운 공간 벡터 RPPWM(Random Position PWM)방식을 제안하였다. 제안한 방식은 마이크로 컨트롤로 적용하기 쉬운 공간벡터 변조에 의하여 각 상의 듀티비를 연산한 다음, 스위칭 순서를 유지하며 각 3상 펄스들의 위치를 변조구간내에서 임의의 위치에 랜덤하게 배치함으로써 RPWM을 구현하는 방식이다. 제안된 방법의 타당성을 검증하기 위하여 MATLAB/SIMULINK를 이용하여 펄스위치의 랜덤화 공각벡터 변조, 인버터 및 3상 유도전동기를 포함하는 전체 시스템을 모델화하였다. 종전의 공각벡턱 PWM 그리고 제안된 RPPWM에 의한 인버터 출력 전압 전류의 고조파 성분을 시뮬레이션에 의하여 비교 검토하였으며 제안된 방법의 유용성을 입증할 수 있었다.

• 전기학회논문지P
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• 제59권2호
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• pp.173-178
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• 2010

Frequency is an important operating parameter of a power system. Due to the sudden change in generation and loads or faults in power system, the frequency is supposed to deviate from its nominal value. It is essential that the frequency of a power system be maintained very close to its nominal frequency. And monitoring and an accurate estimation of the power frequency by timing synchronized signal provided by FDR is essential to optimum operation and prevention for wide area blackout. As most conventional frequency estimation schemes are based on DFT filter, it has been pointed out that the gain error by change in magnitude could cause the defects when the power frequency is deviated from nominal value. In this paper, an advanced frequency estimation scheme using gain compensation for fault disturbance recorders (FDR) is presented. The proposed scheme can reduce the gain error caused when the power frequency is deviated from nominal value. Various simulation using both the data from EMTP package and user's defined arbitrary signals are performed to demonstrate the effectiveness of the proposed scheme. The simulation results show that the proposed scheme can provide better accuracy and higher robustness to harmonics and noise under both steady state tests and dynamic conditions.

• 조명전기설비학회논문지
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• 제21권8호
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• pp.34-43
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• 2007

본 연구에서는 배전시스템 안정성의 요소라 할 수 있는 고조파, 전압변동, Sag/Swell, 신뢰도의 측면에서 배전시스템을 전력품질 측면에서 안정성을 종합적으로 평가하는 방법을 개발하였다. 시스템이 전력품질의 측면에서 얼마나 안정적인가를 정량적으로 평가하기 위해서 AHP(Analytic Hierarchy Process)를 사용하여 종합 전력품질 통합지수를 산정하는 방법을 제안하였다. 또한 몬테카를로 시뮬레이션을 수행함으로서 사고를 고려한 배전계통의 안정성을 평가하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.653-656
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• 2002

In this paper, we present the simulation results of multi-layer VCO(voltage controlled oscillator), which is composed of resonator, oscillator, and buffer circuit, using EM simulator and nonlinear RF circuit simulator. EM simulator is used for obtaining the EM(Electromagnetic) characteristics of conductor pattern as well as designing the multi-layer VCO. Obtained EM characteristics were used as real components in nonlinear RF circuit simulation. Finally the overall VCO was simulated by the nonlinear RF circuit simulator. The material for the circuit pattern was Ag and the dielectric was DuPont 951AT, which will be applied for LTCC process. The structure of multi-layer VCO is constructed with 4 conducting layer. Simulated results showed that the output level was about 4.5 [dBm], the phase noise was -104 [dBc/Hz] at 30 [kHz] offset frequency, the harmonics -8 dBc, and the control voltage sensitivity of 30 [MHz/V] with a DC current consumption of 9.5 [mA]. The size of VCO is $6{\times}9{\times}2$ mm(0.11[cc]).

• Journal of Power Electronics
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• 제18권2호
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• pp.467-481
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• 2018

Modular multilevel converter (MMC)-based high-voltage direct current (HVDC) presents attractive technical advantages and contributes to enhanced system operation and reduced oscillation damping in dynamic MMC-HVDC systems. We propose an advanced small-signal multi-terminal MMC-HVDC based on dynamic phasors and state space for power system stability analysis to enhance computational accuracy and reduce simulation time. In accordance with active and passive network control strategies for multi-terminal MMC-HVDC, the matchable small-signal stability models containing high harmonics and dynamics of internal variables are conducted, and a related theoretical derivation is carried out. The proposed advanced small-signal model is then compared with electromagnetic-transient and traditional small-signal state-space models by adopting a typical multi-terminal MMC-HVDC network with offshore wind generation. Simulation indicates that the advanced small-signal model can successfully follow the electromechanical transient response with small errors and can predict the damped oscillations. The validity and applicability of the proposed model are effectively confirmed.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권7호
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• pp.387-398
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• 2002

In this paper, a new Three-Phase Lead-Lag Random Pulse Position PWM(LL-RPWM) scheme is proposed and implemented for decreasing audible acoustic noise of motor drives. In the proposed RPWM(Random PWM), each of three phase pulses is located randomly in each switching interval. Based on the space vector modulation technique, the duty ratio of the pulses is calculated. Along with the randomization of the PWM pulses, we can obtain the effects of spread spectra of voltage, current as in the case of randomly changed switching frequency. To verify the validity of the proposed LL-RPWM, the simulation and experimental study was tried. Along with the randomization PWM pulses, the space vector modulation is also executed in the C167 micro-controller. The simulation and experimental results show that the voltage and current harmonics are spread to a wide band area and that the audible acoustic noise is reduced by the proposed RPWM method.

• 항공우주기술
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• 제3권2호
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• pp.104-115
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• 2004

본 논문에서는 FTS 수신기(Receiver)의 기저대역(Baseband)부에 적용되어 신호에 포함되는 불필요한 잡음성분을 제거하기 위한 용도의 저역통과필터(Low-Pass Filter)와 톤(Tone)신호를 검출해 내기 위한 톤 필터로 적용 가능한 여러 종류의 필터에 대해 고찰하였고, 이를 바탕으로 Simulation을 통해 적용 가능성을 검토하였다. 서로 다른 형태의 필터는 각각의 목적과 용도에 따라 특성의 차이가 있으므로 어느 하나의 필터 특성이 좋다는 절대적인 기준은 없고 적용하려는 목적과 성능의 필요성에 따라 필터의 형태가 결정되는 상대적인 기준에 의해 결정되게 된다. 이에 따라 본 논문에서는 적용되는 부품 소자의 수를 줄여 무게의 경량화와 소형화를 얻으면서도 요구하는 성능을 만족시킬 수 있는 최적의 필터형태를 제시하였다.