• Title/Summary/Keyword: Q-distortion

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A design for a robust active power filter in unbalanced and distortion source voltages in three-phase four-wire systems (전원전압의 불평형 및 왜곡에 강인한 3상 4선식 전력용 능동 필터의 설계)

  • Min J.K.;Choi J.H.;Kim H.S.;Kim K.H.
    • Proceedings of the KIPE Conference
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    • 2003.07b
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    • pp.729-733
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    • 2003
  • This paper proposed a novel current control strategy on active power filters using p-q-r instantaneous power theory which can compensate the line current harmonics and the neutral line current in unbalanced and/or distorted source conditions in three-phase four-wire systems. The proposed current control method is based on a sinusoidal PWM for fully-digital implementation which was compared with a hysteresis PWM. Simulation results showed good performance of the proposed current control strategy on shunt type APFs.

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CONTROL STRATEGIES FOR SHUNT ACTIVE POWER FILTERS IN DISTORTION SOURCE VOLTAGE SITUATION

  • Yang, Jun;Wang, Zhaoan
    • Proceedings of the KIPE Conference
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    • 1998.10a
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    • pp.876-881
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    • 1998
  • The compensation strategy of shunt active power filters is one of the most important link that determine its compensation characteristics. In this paper, a new interpretation of the instantaneous reactive power theory in three-phase circuits was proposed. A compensation strategy (ip, iq mode) was introduced on the basis of the new interpretation. This compensation strategy was compared with other two compensation strategies(P, q mode and UPF mode). When source voltage is distorted, a sinusoidal, the three compensation strategies are equivalent to each other. When source voltage is distorted, a sinusoidal source current may result only by using ip, iq mode. This is the advantage of ip, iq mode. The result is verified by simulation.

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A Varactor-Tuned RF Tunable Bandpass Filter with Improved Passband Flatness

  • Kim, Byung-Wook;Yun, Du-Il;Yun, Sang-Won
    • Journal of electromagnetic engineering and science
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    • v.2 no.2
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    • pp.124-127
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    • 2002
  • A RF tunable bandpass filter using dielectric resonators and varactor diodes is redesigned to improve the passband flatness. Since the tunable liters are generally of narrow bandwidth and the Q value of the varactor diode is usually very low, the passband flatness is strongly deteriorated by sizeable distortion loss. To remedy this problem, we construct modified Chebyshev type filter by use of network synthesis techniques. The key of modified Chebyshev type filter is the rearrangement of the passband poles to improve the passband flatness. To maintain the constant passband bandwidth, design techniques of input/output stage and coupling windows are also applied. Experimental results show that the passband flatness can be improved by purposed method without any additional RF amplitude equalizer.

Design of Parameters for High Power Static Var Compensator Used Cascade Multilevel Inverter (직렬형 멀티레벨 인버터를 사용한 대용량 무효전력 보상장치의 파라메타 설계)

  • Min, Wan-Ki;Choi, Jae-Ho
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.52 no.4
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    • pp.172-178
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    • 2003
  • This paper examines the application of high voltage static var compensator(SVC) with cascade multilevel inverter which employs H-bridge inverter(HBI). This method has the primary advantage that the number of voltage levels can be increased for a given number of semiconductor devices when compared to the conventional control methods. The SVC system is modeled using the d-q transform which calculates the instantaneous reactive power. This model is used to design a controller and analyze the SVC system. From the mathematical model of the system, the design procedures of the circuit parameters L and C are presented in this thesis. To meet the specific total harmonic distortion(THD) and ripple factor of the capacitor voltage, the circuit parameters L and C are designed. Simulated and experimental results are also presented and discussed to validate the proposed schemes.

A Dead Time Compensation Algorithm of Independent Multi-Phase PMSM with Three-Dimensional Space Vector Control

  • Park, Ouk-Sang;Park, Je-Wook;Bae, Chae-Bong;Kim, Jang-Mok
    • Journal of Power Electronics
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    • v.13 no.1
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    • pp.77-85
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    • 2013
  • This paper proposes a new dead time compensation method of independent six-phase permanent magnet synchronous motors (IS-PMSM). The current of the independent phase machines contains odd-numbered harmonics because of the dead time and the nonlinear characteristics of the switching devices. By using the d-q-n three-dimensional vector analysis, these harmonics can be extracted at the n-axis current. Thus, the current distortion can be compensated by controlling the n-axis current of the IS-PMSM to zero. The proposed method is simple and can be easily implemented without additional hardware setup. The validity of the proposed compensation method is verified with simulations and several experiments.

Design of Passive Parameters for A Cascade Multilevel Inverter Based Static Var Compensator (직렬형 멀티레벨 인버터를 사용한 무효전력보상장치의 수동 파라메타 설계)

  • Min, Wan-Ki;Min, Jun-Ki;Choi, Jae-Ho
    • Proceedings of the KIEE Conference
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    • 2002.06a
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    • pp.125-130
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    • 2002
  • This paper examines the application of high voltage static var compensator(SVC) with cascade multilevel inverter which employs H~bridge inverter(HBI). The SVC system is modeled using the d-q transform which calculates the instantaneous reactive power. This model is used to design a controller and analyze the SVC system. From the mathematical model of the system, the design procedures of the circuit parameters Land C are presented in this thesis. To meet the specific total harmonic distortion(THD) and ripple factor of the capacitor voltage, the circuit parameters Land C are designed. Simulated and experimental results are also presented and discussed to validate the proposed schemes.

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Implementation of Phase-Error Compensation Algorithm in Terrestrial Digital TV Modulator (지상파 디지털 TV 방송용 송신기에서 변조기의 위상오차 보상에 관한 알고리듬 구현)

  • Oh, Inn-Yeal;Yang, Kyung-Seok;Lee, Chul;Mok, Ha-Kyun;Oh, Seong-Hwan
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.6B
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    • pp.1156-1164
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    • 1999
  • In this paper, we have studied the 8 YSB (8 Vestigial Side Band) method which is decided as the standard of modulators for next generation digital TV System. In developing digital TV System, one of the difficult problems is how digital signal can be transmitted to the receiver without any phase distortion. But, phase error is liable to occur by imperfect design, circumstance variation and device degradation. These characteristics result in distortion of 1,0 signal of modulator and interference in adjacent channels. In particular, the interference in modulator of a high power amplifier result in serious problems in adjacent channels. Here we analyzed problems of phase error which are occurred when 8 levels digital signals are modulated to If signal. And we suggested phase error compensation algorithm and discussed the results for adaptation of the algorithm

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Performance Evaluation of Pansharpening Algorithms for WorldView-3 Satellite Imagery

  • Kim, Gu Hyeok;Park, Nyung Hee;Choi, Seok Keun;Choi, Jae Wan
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.34 no.4
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    • pp.413-423
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    • 2016
  • Worldview-3 satellite sensor provides panchromatic image with high-spatial resolution and 8-band multispectral images. Therefore, an image-sharpening technique, which sharpens the spatial resolution of multispectral images by using high-spatial resolution panchromatic images, is essential for various applications of Worldview-3 images based on image interpretation and processing. The existing pansharpening algorithms tend to tradeoff between spectral distortion and spatial enhancement. In this study, we applied six pansharpening algorithms to Worldview-3 satellite imagery and assessed the quality of pansharpened images qualitatively and quantitatively. We also analyzed the effects of time lag for each multispectral band during the pansharpening process. Quantitative assessment of pansharpened images was performed by comparing ERGAS (Erreur Relative Globale Adimensionnelle de Synthèse), SAM (Spectral Angle Mapper), Q-index and sCC (spatial Correlation Coefficient) based on real data set. In experiment, quantitative results obtained by MRA (Multi-Resolution Analysis)-based algorithm were better than those by the CS (Component Substitution)-based algorithm. Nevertheless, qualitative quality of spectral information was similar to each other. In addition, images obtained by the CS-based algorithm and by division of two multispectral sensors were shaper in terms of spatial quality than those obtained by the other pansharpening algorithm. Therefore, there is a need to determine a pansharpening method for Worldview-3 images for application to remote sensing data, such as spectral and spatial information-based applications.

A Study on the Service Reliability and Power Quality Improvement Using Hybrid Type Capacitor Bank (하이브리드 타입 커패시터 뱅크를 이용한 공급신뢰도 및 전력품질 개선 방안 연구)

  • Lee, Hansang;Yoon, Dong-Hee
    • Journal of IKEEE
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    • v.18 no.3
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    • pp.313-319
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    • 2014
  • The objectives of power system operations are to preserve system stability and reliability as well as to supply proper electric power. For an activation of these objectives, voltage and reactive power should be considered. There are a number of types about reactive power sources, and an insertion of shunt capacitor banks are one of the method to support bus voltage adjacent. This paper includes the design procedure to determine the hybrid type capacitor bank configurations on power system to improve stability and reliability. This procedure includes the capacitor bank capacity calculation, reactor type selection, and reactor capacity calculation. The total capacity calculation of capacitor bank is based on the reactive power margin which is calculated through system studies such as, contingency analysis and Q-V analysis. In the second step, the reactor type and its capacity can be determined through the harmonic analysis. This paper shows that the harmonics are decreased by the proposed hybrid type capacitor bank, especially 5th and 7th harmonics.

The Electrical Properties of Li Doped BiNbO4 Ceramic Thick Film Monopole Antenna (Li이 첨가된 BiNbO4 세라믹 후막 모노폴 안테나의 전기적 특성)

  • 정천석;안성훈;안상철;서원경;허대영;박언철;이재신
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.6
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    • pp.558-566
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    • 2003
  • We fabricated thick film monopole antennas using Li-doped BiNbO$_4$ ceramics and investigated their electrical properties as a function of the Li-doping concentration. Compared with undoped BiNbO$_4$ ceramics, addition of Li$_2$CO$_3$ improved dielectric constant by increasing of ionic polarization, but reduced quality value by increasing of lattice distortion. Antenna properties like gain, bandwidth and radiation patterns were also greatly affected by the addition of Li$_2$CO$_3$. With increasing amount of Li$_2$CO$_3$, the bandwidth of ceramic monopole antenna was increased to 81.7 %, but the gain was reduced to -10.03 dBi. Also radiation patterns were so distorted and showed low dB value by increasing of dielectric loss.