• Title/Summary/Keyword: Amplitude unbalance

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Analysis for Operation Characteristics of Induction Motor at Asymmetric Voltage Unbalance (비대칭 전압 불평형에 의한 유도전동기의 동작특성 해석)

  • Kim Jong-Gyeum;Park Young-Jin;Lee Eun-Woong;Kim Il-Jung;Sohn Hong-Kwan;Jeong Jong-Ho;Lee Dong-Ju
    • Proceedings of the KIEE Conference
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    • summer
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    • pp.791-793
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    • 2004
  • Voltage unbalance is generated by the load and impedance mismatching at the 3-phase 4-wire system of customer load. Voltage unbalance factor can be changed by the voltage amplitude or phase angle, and both. A small voltage unbalance is connected to high current unbalance. If the voltage unbalance is generated at the joint system of 1-phase and 3-phase load, Induction motor due to the current unbalance increase is generated loss, noise and torque ripple. In order to analyze the effect by voltage unbalance, it is necessary to the consideration of amplitude and phase angle. In this paper, We analyzed the effects that induction motor is affected by asymmetric voltage unbalance

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Vibration Characteristics of a Synchro Clutch Coupling for Steam Turbine (증기터빈용 Synchro Clutch Coupling의 진동 특성)

  • Shim, Eung-Gu;Lee, Tae-Gu;Moon, Seung-Jae;Lee, Jae-Heon
    • Plant Journal
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    • v.4 no.3
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    • pp.66-72
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    • 2008
  • The vibration of steam turbine is caused by Mass unbalance, Shaft misalignment, Oil whip and rubbing etc. But in turbine which is normally operated and maintained, the Mass unbalance component possesses the greatest portion. Our power plant has two steam turbines in capacity of 200 MW and 135 MW respectively and each turbine is supported by 6 journal bearings. However, we had many difficulties because the vibration amplitude of #3 and #4 Bearings was high during the start-up and operation mode change of steam turbine. But, with this study, we completely solved the vibration problem caused by the mass unbalance of #1 steam turbine. Until a recent date, #3 and #4 bearings which support high pressure turbine for #1 steam turbine had shown about $135{\mu}m$ in vibration amplitude (sometimes it increased to $221{\mu}m$ maximum. alarm: 6 mils, trip: 9 mils) at base load. After applying the study, they decreased to about $45{\mu}m$ maximum. It is a result from that we did not change the setting value of bearing alignment and only changed the assembly position of internal parts in Synchro clutch coupling rachet wheel which links between high pressure turbine and low pressure turbine, and increased the internal gap and machining of the Pawl cage surface. In the operation of steam turbine, if the vibration value increases by 1X, we should reduce the vibration of bearing by weight balancing. However, unless the vibration of bearing is declined by the balancing, we will have to disassemble and check the component and find the cause. In this study, we researched the way to lower mass unbalance that is 1X vibration component which has the greatest portion of vibration generated by steam turbine and we got good result by applying the findings of this study.

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A study on Mass Unbalance Vibration Generated from 200MW Steam Turbine Synchro Clutch Coupling (증기터빈용 Synchro Clutch Coupling에서 발생하는 진동에 관한 연구)

  • Shim, Eung-Gu;Kim, Young-Kyun;Moon, Seung-Jae;Lee, Jae-Heon
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03b
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    • pp.232-235
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    • 2008
  • The vibration of steam turbine is caused by Mass Unbalance, Shaft Misalignment, Oil Whip and Rubbing etc. but in turbine which is normally operated and maintained, the Mass Unbalance component possesses the greatest portion. Our power plant has two steam turbines in capacity of 200MW and 135MW respectively and each turbine is supported by 6 journal bearings. However, we had many difficulties because the vibration amplitude of No 3 and 4 Bearings was high during the start-up and operation mode change of steam turbine. But, with this study, we completely solved the vibration problem caused by the mass unbalance of No 1 steam turbine. Until a recent date, No 3 and 4 bearings which support high pressure turbine for No 1 steam turbine had shown about 135${\mu}$m in vibration amplitude (sometimes it increased to 221${\mu}$m maximum. alarm: 6mils, trip: 9mils) at base load. After applying the study, they decreased to about 40${\mu}$m maximum. It is a result from that we did not change the setting value of Bearing Alignment and only changed the assembly position of internal parts in Synchro Clutch Coupling Rachet Wheel which links between high pressure turbine and low pressure turbine, and increased the internal gap and machining of the Pawl stopper surface. In the operation of steam turbine, if the vibration value increases by 1X, we should reduce the vibration of bearing by weight balancing. However, unless the vibration of bearing is declined by the balancing, we will have to disassemble and check the component and find the cause. In this study, We researched the way to lower mass unbalance that is 1X vibration component which has the greatest portion of vibration generated by steam turbine and We got good result by applying the findings of this study.

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A study on balancing performance of self-compensating liquid balancer (자기보상형 액체 평형장치의 평형잡이 성능에 관한 연구)

  • 양보석;이재무;김원철;고장권
    • Journal of Advanced Marine Engineering and Technology
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    • v.22 no.1
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    • pp.35-41
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    • 1998
  • A Self-compensating liquid balancer is proposed, which consists of the vessel contains liquid available to compensate for rotor unbalance, and the vessel provides four sets of suction pipe and reservior. Under the centrifugal field the liquid moves through the pipe from the side of the unbalance mass to the reservior located on the symmetrically opposite side. The liquid balancer was confirmed experimentally to be useful for the balancing of rotor over the critical speed, and the whirling amplitude after balancing decreases to almost constant value in spite of the location and size of unbalance.

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Performance of Generalized BER for Hierarchical MPSK Signal (계층적 MPSK 신호에 대한 일반화된 BER 성능)

  • Lee Jae-Yoon;Yoon Dong-Weon;Hyun Kwang-Min;Park Sang-Kyu
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.9C
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    • pp.831-839
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    • 2006
  • In this paper, we present an exact and general expression involving two-dimensional Gaussian Q-functions for the bit error rate (BER) of hierarchical MPSK with I/Q phase and amplitude imbalances over an additive white Gaussian noise (AWGN) channel. First we derive a BER expression for the k-th bit of hierarchical 4, 8, 16-PSK signal constellations when Gray code bit mapping is employed. Then, from the derived k-th bit BER expression, we present the exact and general average BER expression for hierarchical MPSK with I/Q phase and amplitude imbalances. This result can readily be applied to numerical evaluation for various cases of practical interest in an I/Q unbalanced hierarchical MPSK system, because the one- and two-dimensional Gaussian Q-functions can be easily and directly computed usinB commonly available mathematical software tools.

Unbalance Response Analysis of Copper Die Casting High Speed Induction Motor (동 다이캐스팅 고속 유도전동기의 불평형 응답 해석)

  • Hong, Do-Kwan;Jung, Seung-Wook;Woo, Byung-Chul;Koo, Dae-Hyun;Ahn, Chan-Woo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.7
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    • pp.642-649
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    • 2012
  • This paper deals with a copper die casting induction motor which has several advantages of motor performance. The developed motor is used as spindle motor in machining center. The dynamic characteristic analysis of rotor is dealt with for precision machining. The critical speed of rotor considering rotation and gyroscopic effect should be above operating speed, 18,000 rpm, and have a 201 % sufficient separation margin. Also, the 3-D unbalance vibration response analysis is performed and enabled the prediction of the expected vibration amplitude by unbalance in high speed. The unbalance vibration responses of each position on the rotor are satisfied with allowable vibration displacement of API 611 standard according to balancing G grade(G 0.4, G 2.5, G 6.3). Copper die casting high speed induction motor is successfully developed and verified by experiment.

Software Resolver-to-Digital Converter for Compensation of Amplitude Imbalances using D-Q Transformation

  • Kim, Youn-Hyun;Kim, Sol
    • Journal of Electrical Engineering and Technology
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    • v.8 no.6
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    • pp.1310-1319
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    • 2013
  • Resolvers are transducers that are used to sense the angular position of rotational machines. The analog resolver is necessary to use resolver to digital converter. Among the RDC software method, angle tracking observer (ATO) is the most popular method. In an actual resolver-based position sensing system, amplitude imbalance dominantly distorts the estimate position information of ATO. Minority papers have reported position error compensation of resolver's output signal with amplitude imbalance. This paper proposes new ATO algorithm in order to compensate position errors caused by the amplitude imbalance. There is no need premeasured off line data. This is easy, simple, cost-effective, and able to work on line compensation. To verify feasibility of the proposed algorithm, simulation and experiments are carried out.

Series Active Power Filters for Source Voltage Unbalance Compensation and Power Factor Correction (전원 불평형과 역률을 보상하는 직렬형 능동전력필터)

  • Jang, Jeong-Ik;Lee, Dong-Choon;Seok, Jul-Ki
    • Proceedings of the KIPE Conference
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    • 2005.07a
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    • pp.498-500
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    • 2005
  • This paper presents a unified control scheme for series-type active power filters combined with shunt passive filters for the source voltage unbalance compensation and the power factor correction simultaneously. The power factor correction is achieved by controlling the amplitude of reactive power current in a series filter as zero in a synchronously rotating reference frame. The proposed algorithm successfully compensates the source voltage unbalance and the power factor. The validity of the proposed scheme has been verified by simulation for a 3-kVA hybrid active power filter system.

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A Parametric Study and an Optimal Design of an ER-SFD Supporting a Rigid Rotor System (강성 회전축계를 지지한 ER-SFD의 parametric study 및 최적설계)

  • 김종립;이남수;이용복;김창호;최동훈
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1999.06a
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    • pp.279-284
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    • 1999
  • This paper presents a parametric study and an optimal design of the ER-SFD supporting a rigid rotor system. An attempt is made to obtain the optimal design of an ER-SFD for a two degree-of-freedom rotor model. Such a simple model is used in order to get a better insight into the physics of the problem, A maximum whirl amplitude, supply pressure and voltage are considered, and a maximum whirl amplitude is minimized over a range of speeds and presented for some values of unbalance mass. The results presented in this paper provide important design information necessary to reduce a whirl amplitude of an ER-SFD.

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An Optimal Design of an ER-SFD Supporting a Rigid Rotor System (강성 회전축계를 지지한 전기 유변 유체 스퀴즈 필름 댐퍼의 최적설계)

  • 이용복;김종립;이남수;김창호;최동훈
    • Tribology and Lubricants
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    • v.17 no.3
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    • pp.216-220
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    • 2001
  • This paper presents a parametric study and an optimal design of the ER-SFD supporting a rigid rotor system. An attempt is made to obtain the optimal design of an ER-SFD for a two degree-of-freedom rotor model. Such a simple model is used in order to get a better insight into the physics of the problem. A maximum whirl amplitude, supply pressure and voltage are considered, and a maximum whirl amplitude is minimized over a range of speeds and presented f3r some values of unbalance mass. The results presented in this paper provide important design information necessary to reduce a whirl amplitude of an ER-SFD.