Fast and Accurate Transient Analysis of Buried Wires and its Applications

An improved finite difference time-domain (FDTD) method based on the telegraph equations of transmission lines is proposed. The original time-domain simulation method that resembles the well-established FDTD scheme based on the Maxwell's equations has been used in this paper to tackle the modeling problems of buried and overhead transmission lines. In this paper, a group of time domain responses of the ground impedance or ground admittance can be extracted analytically by means of a correlation between the ground impedance and the ground admittance. Thanks to the analytical technique, the accuracy of this time-domain solution is improved significantly. As a result, the application of this time-domain algorithm can be greatly expanded beyond the modeling of common transmission lines. By combining with the shunt and series connection difference equations, the method can be used to analyze an entire buried grounding network. Because the correlation between the ground impedance and the ground admittance is related to the propagation constant of electromagnetic waves, the analytical technique makes the propagation velocity unchanged during the iterative calculation. Therefore, the improved FDTD method allows the grounding network to be analyzed more accurately and efficiently.