Implementation of leader development models for prediction of insulation flashover in 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 evaluating the effects of lightning to power systems. This can be achieved in an accurate manner by applying leader development models (LDMs), accounting for the associated physical processes. This work contributes to LDM application to different methodologies/techniques used for the simulation of lightning strikes to power systems, and hence, for insulation coordination studies. This is achieved by identifying and discussing important features related to LDM implementation in a generalized manner not tied to a specific methodology and a specific LDM. Finite Difference Time Domain (FDTD) and ATP-EMTP implementations are introduced to investigate the effects of these elements. They are then employed to assess the lightning performance of a 150 kV single-circuit overhead power line. For this purpose, the minimum lightning currents causing shielding failure flashover and backflashover to the line are computed by means of the two aforementioned simulation methods. Results are compared and discussed considering the differences between methods. For the shielding failure case, identical results were obtained. Differences from <1% up to ∼10% were found for the minimum backflashover current, and up to <5% for the backflashover rate.