S-domain FE Analysis of Magneto-quasi-static Problem Using Discrete Laplace Transform

The frequency domain finite element (FE) method is utilized to study the magneto problem with the large time constant, as it allows for the avoidance of tedious computation to meet steady state in the time domain. However, frequency domain FEM has its limitations; for instance, it cannot consider the initial value in simulations. This paper proposes a s-domain FE method which solves steady-state magnetic field based on initial state. The method can convert the time-dependent excitation onto s-domain using discrete Laplace transform and solve the governing equations in the s-domain. To verify the correctness of this method, a 35kV transformer model is taken as a numerical example to study the magnetic field.