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A Numerical Approach for Lightning Impulse Flashover Voltage Prediction of Typical Air Gaps
Zhibin Qiu,Jiangjun Ruan,Congpeng Huang,Wenjie Xu,Daochun Huang 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.3
This paper proposes a numerical approach to predict the critical flashover voltages of air gaps under lightning impulses. For an air gap, the impulse voltage waveform features and electric field features are defined to characterize its energy storage status before the initiation of breakdown. These features are taken as the input parameters of the predictive model established by support vector machine (SVM). Given an applied voltage range, the golden section search method is used to compute the prediction results efficiently. This method was applied to predict the critical flashover voltages of rod-rod, rod-plane and sphere-plane gaps over a wide range of gap lengths and impulse voltage waveshapes. The predicted results coincide well with the experimental data, with the same trends and acceptable errors. The mean absolute percentage errors of 6 groups of test samples are within 4.6%, which demonstrates the validity and accuracy of the predictive model. This method provides an effectual way to obtain the critical flashover voltage and might be helpful to estimate the safe clearances of air gaps for insulation design.
A Numerical Approach for Lightning Impulse Flashover Voltage Prediction of Typical Air Gaps
Qiu, Zhibin,Ruan, Jiangjun,Huang, Congpeng,Xu, Wenjie,Huang, Daochun The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.3
This paper proposes a numerical approach to predict the critical flashover voltages of air gaps under lightning impulses. For an air gap, the impulse voltage waveform features and electric field features are defined to characterize its energy storage status before the initiation of breakdown. These features are taken as the input parameters of the predictive model established by support vector machine (SVM). Given an applied voltage range, the golden section search method is used to compute the prediction results efficiently. This method was applied to predict the critical flashover voltages of rod-rod, rod-plane and sphere-plane gaps over a wide range of gap lengths and impulse voltage waveshapes. The predicted results coincide well with the experimental data, with the same trends and acceptable errors. The mean absolute percentage errors of 6 groups of test samples are within 4.6%, which demonstrates the validity and accuracy of the predictive model. This method provides an effectual way to obtain the critical flashover voltage and might be helpful to estimate the safe clearances of air gaps for insulation design.
Analysis of Transient Magnetic Force on End‑Winding in the Inverter‑Fed Induction Machine
Liezheng Tang,Jiangjun Ruan,Hengyu Ding,Tao Huang,Hailong Liu 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.1
The increasing harmonics caused by inverter supply have an adverse impact on the end-winding vibration of the induction machine in accelerating failure and adding noise. Therefore, this paper puts forward an approach for end-winding magnetic force calculation in the inverter-fed induction machine. The 2D feld–circuit–motion coupling analysis is used to calculate the stator currents in an induction machine, which are taken as loads in 3D transient magnetic analysis to obtain magnetic force on the end-windings. A three-phase squirrel-cage induction machine was designed and an experiment was carried out on the test motor to validate the proposed model. The simulated stator current, magnetic fux density and magnetic force agree well with both the theoretical analysis and measured results. Finally, a 3-D transient structural simulation was performed to further analyze the end-winding vibration. However, there is some diference of end-winding vibration acceleration between the simulation and experiment in harmonic components. The above deviation is probably attributed to the structure simplifcation of the induction machine. Thus, the developed simulation model can calculate the magnetic force on end-winding with reasonable accuracy, but it is advisable to perform an experimental study to fully analyze the vibration characteristics of end-winding.