• Title/Summary/Keyword: End Winding

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Vibration Analysis of the End-winding of Large Generator for Fossil Power Plant under Electromagnetic Excitation (대형 화력 발전용 발전기 권선단부의 전자기력에 의한 진동 해석)

  • 김철홍;주영호
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.350-355
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    • 2003
  • This paper presents results of vibration analysis of a end-winding of large generator for fossil power plant. A finite element analysis using a commercial S/W is performed to calculate alternating electromagnetic forces, mainly of 120㎐ in 60㎐ machines, acting on the end-winding, and then to calculate forced response of the end-winding under electromagnetic forces. Also, this paper presents analytical and experimental modal analysis results of generator end-winding to validate FE model. We calculated forced response of end-winding on 120㎐, double rotating frequency. These results will be used to evaluate structural reliability of end-winding and applied to update model.

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Analysis of Vibration and Electromagnetic Forces on a Generator End-winding for 500 MW Fossil Power Plant (500MW 급 대형 발전기 권선단부의 전자기력과 동특성 해석)

  • 김철홍;주영호
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.11b
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    • pp.826-831
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    • 2001
  • Electromagnetic forces generate vibrations in the end-winding of large generators. A finite element analysis using a commercial S/W is performed to calculate electromagnetic force of end-winding in two pole generator for 500 MW fossil power plant. Also, this paper presents analytical and experimental modal analysis results of generator end- winding. Using validated FE model, 3D electromagnetic model which computes the forces on the end-winding is coupled with a 3D mechanical model which calculates the dynamic displacement and stress under electromagnetic forces. These results will be used to evaluate reliability of end-winding and applied to update model.

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Comparison of Biot-Savart's Law and 3D FEM in the Study of Electromagnetic Forces Acting on End Winding

  • Kim, Ki-Chan
    • Journal of Electrical Engineering and Technology
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    • v.6 no.3
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    • pp.369-374
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    • 2011
  • An induction motor operated with high voltage source generally generates high current in starting mode and has a long transient time after being started. This large and sustaining starting current causes the end windings of the stator to have excessive electromagnetic force. This force is the source of vibration and has a negative and serious influence on the insulation of end windings. Therefore, designing the end winding part with an appropriate support system is needed. To design the support ring enclosing the end windings, we analyze the distribution of electromagnetic force on the end windings by applying the Biot-Savart's law and the 3D finite element method (FEM), and comparing two simulation methods. Finally, we verify the safety of the support structure of the end winding part using stress analysis, which is analyzed with the electromagnetic forces from the 3D FEM simulation.

Rotor fan effects on end winding heat transfer in totally enclosed fan cooled induction motor (전폐형 유도전동기 엔드와인딩 표면의 열전달에 미치는 회전자팬의 영향)

  • Yun, Myeong-Geun;Go, Sang-Geun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.21 no.7
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    • pp.928-938
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    • 1997
  • The end winding is an important part in induction motor for thermal analysis. But there is little information on the heat transfer coefficient of that surfaces because of geometrical complexity. So our experimental object is to know the heat transfer coefficient of end winding and find the optimum design parameter of rotor fan. Carbon coated papers were used for a uniform heat generating surfaces which were easy to fabricate. The experiments of some parameters were performed as varying rotation speed of rotor fan. We obtained the local and average Nusselt number of the end winding surfaces by correcting radiation and conduction losses errors. The results showed that the average Nusselt number increased with rotor fan blade number and width but decreased with end winding length. However, the increasing limits existed in the case of rotor fan width and blade number. So optimum design value were obtained for rotor fan width and blade numbers.

Shorted-Turn Diagnosis Test for Generator Rotor Windings using Low Voltage Pulse Signal (저전압 펄스신호를 이용한 발전기 회전자 턴단락 진단)

  • Lee, Young-Jun;Kim, Byung-Rae;Whang, Young-Ha
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.2019_2020
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    • 2009
  • A recurrent surge oscillograph(RSO) test was performed at the Taean thermal power plant on #5 turbine generator. The test was conducted using a rotor reflectometer and digital oscilloscope. A DC voltage step is applied to each end of the rotor winding in turn. Each reflected wave, at the input end of the winding, is monitored and the two waveforms are superimposed automatically and monitored on a single channel oscilloscope. As the half windings in a rotor are identical, the two waveforms monitored at each end of the rotor will also be identical for a healthy winding. A winding with a fault will cause different voltages to be monitored at the two ends.

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Analysis of Off-Line and On-Line Partial Discharge in High Voltage Motor Stator Windings

  • Kim, Hee-Dong;Kong, Tae-Sik;Lee, Sang-Kil;Kim, Beom-Soo;Kim, Doo-Young
    • Journal of Electrical Engineering and Technology
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    • v.10 no.3
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    • pp.1086-1092
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    • 2015
  • The off-line and on-line partial discharge (PD) in the stator winding of three high-voltage (HV) motors (1,400 HP, 6.6 kV) is measured and analyzed in this paper. The off-line PD is measured at high values between 24,300 ~ 36,100 pC after 18 years of motor operation. Spare replacement motors were not available for testing the degree of deterioration of the stator windings in standstill status. Therefore, on-line periodic analysis was conducted to monitor the trend of PD after installing a ceramic sensor (110 pF, 6.6 kV) in the terminal box for each phase of each motor. In the stator winding of the No.1 and No.2 HV motors, which showed high magnitudes of off-line PD and low magnitudes of on-line PD, defects are expected to appear in the neutral end of the winding. On the contrary, in the stator windings of the No.3 HV motor, which exhibits high off-line and on-line PD magnitude, defects are expected to appear in the terminal end of the winding where a voltage close to the phase voltage is applied.

Analysis of the Insulation aging for the stator winding (고정자권선의 절연열화 특성분석)

  • Oh, Bong-Keun;Choi, Kyo-Nam;Han, Chang-Dong;Lim, Kee-Joe
    • Proceedings of the KIEE Conference
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    • 2006.07e
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    • pp.23-24
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    • 2006
  • Stator winding of hydro generator is gradually deteriorated by multi-stress and steady degradation of insulation results in insulation breakdown. The region where insulation breakdown occurs in stator winding is part where the multi-stress causes the defect of insulation material and electrical stress has been concentrated. Therefore, we judged locations of insulation breakdown to be varied according to various stress factors in service. In this paper, we drew the stator winding of hydro generators which has run for a long time and separated it into 3 parts(central part, end winding part, drawing part) according to the positions laid on the core. We performed electrical and thermal stress on these specimens for 1000 hrs under the same condition, measured the condition regularlyand analyzed the insulation status of each winding by performing partial discharge test. In addition, we analyzed the trend of partial discharge concerning specimens that caused the insulation breakdown during aging.

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An Optimized Control Method Based on Dual Three-Level Inverters for Open-end Winding Induction Motor Drives

  • Wu, Di;Su, Liang-Cheng;Wu, Xiao-Jie;Zhao, Guo-Dong
    • Journal of Power Electronics
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    • v.14 no.2
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    • pp.315-323
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    • 2014
  • An optimized space vector pulse width modulation (SVPWM) method with common mode voltage elimination and neutral point potential balancing is proposed for an open-end winding induction motor. The motor is fed from both of the ends with two neutral point clamped (NPC) three-level inverters. In order to eliminate the common mode voltage of the motor ends and balance the neutral point potential of the DC link, only zero common mode voltage vectors are used and a balancing control factor is gained from calculation in the strategy. In order to improve the harmonic characteristics of the output voltages and currents, the balancing control factor is regulated properly and the theoretical analysis is provided. Simulation and experimental results show that by adopting the proposed method, the common mode voltage can be completely eliminated, the neutral point potential can be accurately balanced and the harmonic performance for the output voltages and currents can be effectively improved.

A New Method for Elimination of Zero-Sequence Voltage in Dual Three-Level Inverter Fed Open-End Winding Induction Motors

  • Geng, Yi-Wen;Wei, Chen-Xi;Chen, Rui-Cheng;Wang, Liang;Xu, Jia-Bin;Hao, Shuang-Cheng
    • Journal of Power Electronics
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    • v.17 no.1
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    • pp.67-75
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    • 2017
  • Due to the excessive zero-sequence voltage in dual three-level inverter fed open-end winding induction motor systems, zero-sequence circumfluence which is harmful to switching devices and insulation is then formed when operating in a single DC voltage source supplying mode. Traditionally, it is the mean value instead of instantaneous value of the zero-sequence voltage that is eliminated, through adjusting the durations of the operating vectors. A new strategy is proposed for zero-sequence voltage elimination, which utilizes unified voltage modulation and a decoupled SVPWM strategy to achieve two same-sized equivalent vectors for an angle of $120^{\circ}$, generated by two inverters independently. Both simulation and experimental results have verified its efficiency in the instantaneous value elimination of zero-sequence voltage.

A Study on the Partial Discharge Wave Propagation along Stator Winding (회전기 권선의 펄스 전송특성 연구)

  • Kang, Dong-Sik;Sim, Woo-Yong;Hwang, Don-Ha;Kim, Yong-Joo
    • Proceedings of the KIEE Conference
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    • 2003.07b
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    • pp.738-740
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    • 2003
  • A lot of R&D on the diagnosis of stator winding insulation for large rotating machines has been carried out since the 1970s. The on-line partial discharge measurement has proved to be an effective technique in the evaluation of the state of stator insulation in high voltage rotating machines. It is well known that if the discharge pulses propagate through the winding conductor, they are attenuated and delayed. In the present study, to investigate the attenuation and the time delay of discharge pulses through the winding conductor, a series of tests were conducted using a model coils and slot. Thus it could be concluded that while the high frequency pulse propagates in radiation or end-winding coupling modes, the low frequency one does in a series mode through the coil conductor.

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