Time-Domain Finite Element Method for Calculation of Transient Electric Field in Combined Insulating Structures Considering the Influence of Dielectric Relaxation
Wen Teng, Cui Xiang, Li Xuebao, Liu Sijia, Zhao Zhibin
State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing 102206 China
Abstract：In the actual operation of electric power equipment, it may be subjected to transient voltage excitations such as switching surge voltage, lightning impulse voltage and so on. In addition, with the widespread application of power electronic devices in DC power transmission equipment, the voltage that the insulation structure of the internal devices bears is not traditional AC voltage or DC voltage, but positive repetitive square wave voltage. In order to study the electric field characteristics of the insulating structure in these equipment or devices under transient voltage excitation, it is necessary to calculate the transient electric field distribution under the electro-quasistatic field. Insulating materials exhibit dielectric relaxation phenomenon in the alternating electric field, and their permittivity is a frequency-dependent function in the frequency domain. Due to the short duration time and rapid change of the transient voltage, the corresponding frequency spectrum is wide. Therefore, the calculation of the transient electric field under transient voltage excitation needs to consider the dielectric relaxation characteristics. For this reason, this paper proposes a time-domain finite element method which considers the dielectric relaxation process of the materials. In this paper, the dielectric relaxation phenomenon of the material is characterized by the time-varying permittivity. The governing equation is discretized in time and space. The time-domain finite element equation and the constrained electric field equation on the boundary are derived. Then, the effectiveness of the calculation method proposed in this paper is verified by comparing the experimental results and calculation results of the polarization current of PEEK material under the step voltage. Finally, the distribution characteristics of the transient electric field of the combined insulating structure considering the dielectric relaxation characteristics of the material under transient voltage excitation are analyzed.
文腾, 崔翔, 李学宝, 刘思佳, 赵志斌. 考虑介质介电驰豫影响时瞬态电场计算的时域有限元法[J]. 电工技术学报, 2022, 37(7): 1735-1745.
Wen Teng, Cui Xiang, Li Xuebao, Liu Sijia, Zhao Zhibin. Time-Domain Finite Element Method for Calculation of Transient Electric Field in Combined Insulating Structures Considering the Influence of Dielectric Relaxation. Transactions of China Electrotechnical Society, 2022, 37(7): 1735-1745.
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