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Electronic supplementary material The online version of this article (https://doi.org/10.1186/s40880-019-0353-0) contains supplementary material, which is available to authorized users.
In this paper, the frequency finite element method, combined with fixed point method and linearization method, is adopted to compute the anisotropic nonlinear periodic electric field in oil-paper insulation under the AC-DC hybrid voltage, which contains many high order harmonics. The field equation is derived based on the qua-static field theory, and the formula of selecting fixed-point conductivity...
A finite element method, which directly uses the node electric scalar potentials and node charge densities as variables, is used to predict the electric field and charge density distributions under polarity reversal (PR) voltage. The penalty method is adopted to impose the Dirichlet boundary values and the Crank–Nicolson (C-N) algorithm is then used to solve the transient equation. The surface node...
A state space finite element method is presented for the calculation of transient electric field in oil-immersed insulation system of converter transformer. Firstly, the state equation is derived based on the quasi-static electric field theory, combined with the given boundary value using the penalty method, which has a clear physical meaning. Secondly, the state equation is solved in a fine integration...
An adaptive time-step algorithm has been proposed in this paper based on each step's temporal local truncation error of C-N (Crank-Nicholson) method. Utilizing the characteristics of polarity reversal voltage, the oscillation of time step at the discontinuity of the derivative of polarity reversal voltage has been avoided successfully by the combination of backward Euler method. The algorithm is verified...
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