
478 Power System Transients
conducting earth. Because the surge impedance of the conductor is evaluated
as Z
s
= 60 ln(2 h/r) = 406 Ω, the current amplitude should be I = E/2Z
s
= 2.46 A.
The results in Figure 7.10 are far from the theoretical estimation with the
exception of case 1-4, d = 0 with double precision. In fact, an FDTD simula-
tion depends heavily on the absorbing boundary conditions, the accuracy of
which is a function of the stabilization coefcient, oating point operation,
time step, etc. [38], when the working space and cell size are xed. Therefore,
preliminary simulations to investigate the effect of the working space and
cell ...