• Title/Summary/Keyword: Series harmonic resonance

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Resonance Characteristics Analysis of Grid-connected Inverter Systems based on Sensitivity Theory

  • Wu, Jian;Han, Wanqin;Chen, Tao;Zhao, Jiaqi;Li, Binbin;Xu, Dianguo
    • Journal of Power Electronics
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    • v.18 no.3
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    • pp.746-756
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    • 2018
  • Harmonic resonance exists in grid-connected inverter systems. In order to determine the network components that contribute to harmonic resonance and the composition of the resonant circuit, sensitivity theory is applied to the resonance characteristic analysis. Based on the modal analysis, the theory of sensitivity is applied to derive a formula for determining the sensitivities of each network component parameter under a resonance circumstance that reflects the participation of the network component. The solving formula is derived for both parallel harmonic resonance and series harmonic resonance. This formula is adopted to a 4-node grid-connected test system. The analysis results reveal that for a certain frequency, the participation of parallel resonance and series resonance are not the same. Finally, experimental results demonstrate that the solving formula for sensitivity is feasible for grid-connected systems.

A High Gain and High Harmonic Rejection LNA Using High Q Series Resonance Technique for SDR Receiver

  • Kim, Byungjoon;Kim, Duksoo;Nam, Sangwook
    • Journal of electromagnetic engineering and science
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    • v.14 no.2
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    • pp.47-53
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    • 2014
  • This paper presents a high gain and high harmonic rejection low-noise amplifier (LNA) for software-defined radio receiver. This LNA exploits the high quality factor (Q) series resonance technique. High Q series resonance can amplify the in-band signal voltage and attenuate the out-band signals. This is achieved by a source impedance transformation. This technique does not consume power and can easily support multiband operation. The chip is fabricated in a $0.13-{\mu}m$ CMOS. It supports four bands (640, 710, 830, and 1,070MHz). The measured forward gain ($S_{21}$) is between 12.1 and 17.4 dB and the noise figure is between 2.7 and 3.3 dB. The IIP3 measures between -5.7 and -10.8 dBm, and the third harmonic rejection ratios are more than 30 dB. The LNA consumes 9.6 mW from a 1.2-V supply.

Analysis of Impedance Performance for Condenser by Harmonic Current Source (고조파 전류원에 의한 콘덴서 임피던스 특성 해석)

  • Kim, Jong-Gyeum;Park, Young-Jeen
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.25 no.4
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    • pp.57-64
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    • 2011
  • Most of the user has been used linear load and non-linear load. The former is usually inductive load which is needed power factor compensation, the latter is power conversion system device. Actually two kinds of load is used together in the customer application. Generally capacitor is used for power-factor compensation of inductive load and reduction harmonics of non linear load with reactor. Non-linear load generates harmonic current for its energy conversion process. If harmonic current pass along the low impedance side of distribution system, the magnification of voltage and current is appeared by the series and parallel resonance. As a result, condenser has received a bitter electrical stress by the harmonic component. In this paper, we analyzed that how resonance is changed by the 5-th harmonic current pattern and proposed an alternative plan for non-magnification.

Analysis for Electrical Stress of Power Capacitor (전력용 커패시터의 전기적 스트레스 해석)

  • Kim, Jong-Gyeum;Park, Young-Jeen;Lee, Eun-Woong;Lee, Dong-Ju
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.57 no.4
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    • pp.370-376
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    • 2008
  • Power capacitors is widely used for power factor correction and component of passive filter in the user power systems. Recently, application of non-linear load is gradually increased. Non-linear load produces harmonic components of current. There are series resonance and parallel resonance when capacitors are applied in the user electrical application. If this harmonic component matches resonance, voltage and current is magnified and has severely an influences on capacitor. This paper purposes a new method for the magnitude of voltage and current by the frequency scan analysis without equivalent circuit for the actual circuit at the resonance condition.

Resonance Investigation and Active Damping Method for VSC-HVDC Transmission Systems under Unbalanced Faults

  • Tang, Xin;Zhan, Ruoshui;Xi, Yanhui;Xu, Xianyong
    • Journal of Power Electronics
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    • v.19 no.6
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    • pp.1467-1476
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    • 2019
  • Grid unbalanced faults can cause core saturation of power transformer and produce lower-order harmonics. These issues increase the electrical stress of power electronic devices and can cause a tripping of an entire HVDC system. In this paper, based on the positive-sequence and negative-sequence impedance model of a VSC-HVDC system as seen from the point of common connection (PCC), the resonance problem is analyzed and the factors determining the resonant frequency are obtained. Furthermore, to suppress over-voltage and over-current during resonance, a novel method using a virtual harmonic resistor is proposed. The virtual harmonic resistor emulates the role of a resistor connected in series with the commutating inductor without influencing the active and reactive power control. Simulation results in PSCAD/EMTDC show that the proposed control strategy can suppress resonant over-voltage and over-current. In addition, it can be seen that the proposed strategy improves the safety of the VSC-HVDC system under unbalanced faults.

Performance Analysis for Passive Filter Considering Allowable Limits of Tolerance (오차의 허용범위를 고려한 수동형 필터의 특성 해석)

  • Kim, Jong-Gyeum;Kim, Il-Jung
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.58 no.1
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    • pp.38-43
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    • 2009
  • Reactors are connected with capacitors to passive filter circuits for reducing harmonics caused by power conversion application. This passive filter frequently gets out of order by voltage and current stress. Especially filter reactor has too much voltage harmonics components, its trouble rate is higher than capacitor. In this paper, we analyzed voltage and current of reactor and capacitor used for passive filter by simulation and measurement. If reactor has a tolerance on variation of reactance value, series resonance frequency is different from originally filter design frequency and parallel resonance can be generated at the close point of the former. Because filter absorbs harmonic component of non-linear load, much of harmonic voltage has been impacted on reactor.

Active Nonlinear Vibration Absorber for a Nonlinear System with a Time Delay Acceleration Feedback under the Internal Resonance, Subharmonic, Superharmonic and Principal Parametric Resonance Conditions Simultaneously

  • Mohanty, S;Dwivedy, SK
    • Journal of Aerospace System Engineering
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    • v.13 no.5
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    • pp.9-15
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    • 2019
  • In this paper, dynamic analysis of a nonlinear active vibration absorber is conducted with a time delay acceleration feedback to suppress the vibration of a nonlinear single degree of freedom primary system. The primary system consisting of linear and nonlinear cubic springs, mass, and damper is subjected to the multi-harmonic hard excitation with a parametric excitation. It is proposed to reduce the vibration of the primary system and the absorber by using a lead zirconate titanate (PZT) stack actuator in series with a spring in the absorber which configures as an active vibration absorber. The method of multiple scales (MMS) is used to obtain the approximate solution of the system under the internal resonance, subharmonic, superharmonic, and principal parametric resonance conditions simultaneously. Frequency and time responses of the system are investigated considering a delay in the feedback for the various parameters of the absorber configuration and controlling force.

Design and Application of Harmonic Passive Filter (고조파 수동필터의 설계 및 적용)

  • Jeon, Jeong-Chay;Kim, Jae-Hyun;Yoo, Jae-Geun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.11
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    • pp.5397-5402
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    • 2012
  • Accidents involving electric equipment and economical loss by power quality deterioration related to harmonics show a rising tendency A passive filter is economic and efficient in suppressing harmonics but many engineers and designers are reluctant to install a passive filter to defect harmonics at their power system because of problems such as harmonic amplification and the probability of generating series or parallel resonance with the power system. This work introduces that passive filters will be very available to defeat harmonic problems of the power system if passive filters are well designed. We describe method and process of harmonic passive filter design. And the passive filter for the power system having harmonic problems due to use of nonlinear loads like as 100HP DC motor system, an extruding machine, an air blower and other loads are designed. Experimental results verify the performance of the passive filter designed by the described method and procedure.

Research for Protection Relay of Static Condenser Bank (SC 전용 보호계전기 개발)

  • Jeong, J.K.;Yun, S.Y.;Kim, S.J.;Kim, K.G.
    • Proceedings of the KIEE Conference
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    • 2006.05a
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    • pp.48-50
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    • 2006
  • SC(Static Condenser) in KEPCO is used in voltage control and power factor compensation. Currently KEPCO uses SC to 154kv 50MVA and 23kv SMVA. It is not important in old days because a SC bank accident has no effect on power system. But we are interested in the SC bank for power quality in these days. The SC Bank has a reactor and a condenser using series connection. It is operated in critical point for resonance circuit normally. Therefore the SC bank has a small reliability against other Power instruments. If a 4th harmonic frequency as a resonance frequency is supplied in system, the condenser is damaged because of a resonance current. And a trip and a closing for CB(Circuit Breaker) in many times will have a big influence of SC bank destruction. General OCR(Over Current Relay) observing SC bank is not useful for this protection We think that protection relay must be have the SC bank characteristics. A solution for this problem is active Power, resonance frequency and impedance.

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Nonlinear Vibrations of Piezoelectric Microactuators in Hard Disk Drives (하드디스크 드라이브용 압전형 마이크로 액추에이터의 비선형 진동 특성)

  • Jeong, Deok-Yeong;Lee, Seung-Yeop;Kim, Cheol-Sun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.12
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    • pp.2002-2008
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    • 2001
  • Nonlinear vibration characteristics of a piezoelectric-type micro actuator used for hard disk drives are experimentally studied. The nonlinear characterisitics include hysteresis, superharmonic resonance, jump phenomenon, and shifting of natural frequencies. The vibration modes and frequencies of the commercial actuator of the Hutchinson's Magnum series are measured using a laser vibrometer. From harmonic excitation to the PZT acturator, we observe interesting hysteresis patterns with 3 times input frequency. It is shown that the micro actuator has the typical 3 times superhamonic resonances coupled to the first torsional and sway modes of the suspension.