• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.1
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• pp.103-111
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• 2003

With the proliferation of nonlinear loads such as personal computer in an educational building, high neutral harmonic currents have been observed. High neutral currents in three-phase four ire distribution power systems can cause tots of harmonic problems such as overloaded neutral conductors and malfunction of protective equipment. On-site measurements of harmonic currents and voltages were made and the corresponding equivalent circuits was developed. The circuit model under study was simulated numerically and graphically through the use of the software MATLAB. Simulation results verifying the effect of a single-tuned passive filter for the neutral harmonic current reduction are presented.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.6
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• pp.35-42
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• 2006

Large steel industries have nonlinear loads including electric arc furnaces. These nonlinear loads generate harmonic currents and create distortions on the sinusoidal voltage of the power system. This paper provides an in depth analysis on harmonics field measurement of the electric arc furnace loads, adding a single-tuned filter at the customer bus for reducing harmonic distortion and harmonics assessment by the international harmonic standards IEC 61000-3-6 and IEEE Std. 519. The EDSA program was used as a simulation tool for the case study.

• Current Optics and Photonics
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• v.2 no.1
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• pp.27-33
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• 2018

We report the physical implementation of a tunable photonic microwave delay line filter based on injection locking of a single Fabry-Perot laser diode (FP-LD) to a reflective semiconductor optical amplifier (RSOA). The laser generates equally spaced multiple wavelengths and a single tapped-delay line can be obtained with a dispersive single mode fiber. The filter frequency response depends on the wavelength spacing and can be tuned by the temperature of the FP-LD varying lasing wavelength. For amplitude control of the wavelengths, we use gain saturation of the RSOA and the offset between the peak wavelengths of the FP-LD and the RSOA to decrease the amplitude difference in the wavelengths. From the temperature change of total $15^{\circ}C$, the filter, consisting of four flat wavelengths and two wavelengths with slightly lower amplitudes on both sides, has shown tunability of about 390 MHz.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.188-192
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• 2003

A multilayer two-stage LC bandpass filter using low-temperature cofired-ceramic (LTCC) is proposed in this paper. The proposed bandpass filter is composed of two ceramic substrates with different dielectric constant instead of single ceramic material from top to bottom layer. The bandpass filter size is $2.0 mm{\times}1.2 mm{\times}0.8 mm$. Positioning of attenuation polefrequency, importance parameter for a performance of filter, is discussed using even-odd mode analysis by tuned capacitance of coupling capacitor and those results is implemented to LTCC filter circuit. Measured filter performances show that the insertion losses are -4.5dB, -4.1dB at 2.45GHz, 2.75GHz and the return losses are -8.5dB, 8.7dB.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.903_904
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• 2009

본 논문에서는 대표적인 고조파 저감기법인 단일동조 수동고조파필터(single-tuned Passive Harmonic Filter)의 설계 시에 반드시 고려해야 할 최적의 동조계수($\delta$)와 양호도(Q)값의 결정 방법을 제안하였다. 두 값들은 실 사례를 통하여 결정하였고, 결정된 값들은 보드선도를 이용한 주파수 영역 해석을 수행한 후 최종적으로 이 값들을 반영하여 설계된 수동고조파필터의 성능확인을 통하여 본 논문에서 결정한 두 값들의 적합성을 평가하였다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.3
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• pp.81-87
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• 2000

The increasing use of non-linear loads such as power electronics draw highly distorted currents from the utility system. High harmonics currents and voltages will cause equipment damage and disturb the plant operation. The common solution to harmonics problem is to use harmonics filters. In this paper simulation results used the EDSA harmonics analysis program verifying the effects of the single-tuned filter for harmonic elimination are presented.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.4
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• pp.313-320
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• 2006

In this paper, a design approach of LC trap filter for output side harmonic reduction of single phase NPC multilevel inverter is proposed, and THD of the output voltage and harmonic FFT of the output current are analyzed. The proposed filter consists of a conventional LCR filter cascaded with an LC trap filter and it is tuned to inverter switching frequency. A NPC multilevel inverter inverter is used an inverter system for high power application and DSP(TMS320C31) is used for the controller. The effectiveness of the proposed system confirmed through simulation and experimental results.

• ETRI Journal
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• v.28 no.3
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• pp.401-404
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• 2006

A new log-domain first-order multifunction filter is proposed in this letter. The proposed filter is systematically derived using the state-space synthesis procedure from a corresponding block diagram. It provides low-pass (LP), high-pass (HP), and all-pass (AP) responses simultaneously for a single input signal. The filter circuit has a very simple structure since it uses only bipolar junction transistors (BJTs) and a grounded capacitor. It can be electronically tuned by changing an external current. The filter has a greater bandwidth due to its inherent current-mode and log-domain operations. PSPICE simulations are given to confirm the theoretical analysis.

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.78-90
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• 2017

This paper presents the design of closed loop controllers operating a single-phase AC-DC three-level converter for improving power quality at AC mains. Closed loop inhibits outer voltage controller and inner current controller. Simulations of three level converter with three different voltage and current controller combinations such as PI-Hysteresis, Fuzzy-Hysteresis and Fuzzy tuned PI-Hysteresis are carried out in MATLAB/Simulink. Performance parameters such as input power factor and source current total harmonic distortion (THD) are considered for comparison of the three controller combinations. The fuzzy-tuned PI voltage controller with hysteresis current controller combination provides a better result, with a source-current THD of 0.93% and unity power factor without any source side filter for the three level converter. For load variations of 25% to 100%, a THD of less than 5% is obtained with a maximum value of only 1.67%. Finally, the fuzzy-tuned PI voltage with hysteresis controller combination is implemented in a Xilinx Spartan-6 XC6SLX25 FPGA board for experimental validation of power quality enhancement. A prototype 100 W, 0-24-48 V as output converter is considered for the testing of controller performance. A source-current THD of 1.351% is obtained in the experimental study with a power factor near unity. For load variations of 25% to 100%, the THD is found to be less than 5%, with a maximum value of only 2.698% in the experimental setup which matches with the simulation results.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.898-899
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• 2008

본 논문에서는 3상 정류기부하에서 주로 발생하는 5차, 7차등의 저차 고조파를 제거하기 위하여 간단한 구조와 경제성이 있는 Single-tuned Second-order Filter를 설계하였다. 사례연구는 원자력발전소 무정전전원계통(UPS)의 임의의 한 모선을 대상으로 하였으며 계통을 모델링하여 분석한 결과를 토대로 수동필터를 설계하였다. 설계된 필터는 범용 컴퓨터프로그램인 PSIM을 이용하여 시뮬레이션을 수행하였으며 시뮬레이션 결과 해당차수의 고조파를 현저하게 감소시키는 양호한 결과를 얻었다.