Using Subgridding FDTD Method to Incorporate Air Gap Breakdown in the Analysis of Lightning Induced Voltage

ABSTRACT

A subgridding formulation of Agrawal coupling equations of transmission line with branch and distributed electromagnetic excitation is proposed. This algorithm enables us to solve the transmission line system using different temporal and spatial step on different branches. The method is used to calculate the lightning induced over-voltage on the transmission line installed with air gap component branch. The air gap is modeled by disruptive effect method with small time step, while the transmission line is simulated using large time step. With the help of this method, the simulation of transmission line with air gap component can avoid long time computation. As an example, the protection effectiveness of surge arrester with series air gap is studied using the proposed method.

Keywords:

Transmission lines, Finite difference time domain methods, Subgridding, Agrawal coupling equations, Air gaps.