Simulation of lightning-transient responses of grounding systems using the RBF-FDTD method

In this paper, we use a non-uniform transmission line model, in which the per-unit length parameters (L(x,t), G(x,t), and C(x,t)) are dependent on space and time proposed by Yaqing Liu et al [4], to simulate lightning-transient voltages of grounding systems. In this work, the electromagnetic coupling between different parts of grounding systems is taken into account and the influence of the vertical rods on grounding grids is also considered. To solve telegrapher's equations of grounding systems, we propose a new numerical method that is developed from the MQ-FDM [8] and called the Radial Basis Function - Finite Difference Time Domain (RBF-FDTD) method. The RBF is used to find the FD approximations of spatial and temporal derivatives. In particular, with choosing the `optimal' shape parameter of the RBF, the result shows that the RBF-FDTD solution is higher accurate than the FDTD solution. The proposed method is used to simulate and evaluate the transient voltages of some horizontal conductors and grounding grids. The results show that our proposed method is very suitable for studying the solutions of telegrapher's or EM coupling equations of all transmission lines in EMC problems with higher accuracy.