Calculation of distribution parameters for Research on Propagation Characteristic of PD in Transformer Winding

A simulation model of a 180 turns continuous disc type transformer winding was used to study the propagation characteristics of partial discharge (PD) based on multiconductor transmission line (MTL) theory. In order to obtain distribution parameters of unit length of windings, two 2D axial symmetric finite element(FE) models are set up under ANSYS environment. The electromagnetic FE model is used to calculate the capacitance distribution parameters (K) and the time harmonic magnetic FE model used for inductance(L) and resistance(R) parameters. In calculation of K matrix, a modified method is proposed which decrease distinctly computer cost without more loss of accuracy. For the evaluation of L and R parameter of transformer with iron core in high frequency, the skin effect of wire and core is taken into consideration. The FE meshes are controlled subtly in accordance with skin depth. The frequency-dependent parameters are calculated accurately by time harmonic magnetic field analysis. The proposed methods of calculating parameters are helpful to research on propagation characteristic of PD pulses in electric equipments.