Finite difference time domain implementation of leader development models for lightning studies

The prediction of the behavior of long air gaps and insulators when stressed by fast-front overvoltages of non-standard waveshape is crucial for lightning studies. This can be achieved in a more accurate manner by using a leader development model. This work presents a Finite Difference Time Domain (FDTD) implementation of leader development models for lightning studies with emphasis on power lines. The proposed FDTD implementation technique is validated against an ATP-EMTP implementation as well as against literature data. Using the FDTD implementation, the minimum lightning current causing backflashover of a 150 kV single-circuit power line and the backflashover rate, BFR, of the line are estimated both as affected by the power-frequency tower ground resistance and the AC operating voltage of the line. The BFR of the evaluated line is higher when equipped with arcing horns and when the leader predischarge current is not simulated.