Effect of multilayer soil on the switching transient in substations

In order to research the transient current and voltage along the busbar in substations, the ground return impedance of aerial multiconductor transmission lines above a multilayer soil is researched and its time-domain expression is obtained by using vector fitting method. After the algorithm is testified, the effect of the multilayer soil is included in the finite-difference time-domain method based on recursive convolution. The proposed method is demonstrated to give the same results as the famous software EMTP, and to have a little difference from the results of method of moment. Finally, some examples in substations are analyzed to illustrate the effect of the soil on the transient.