Lightning Performance Evaluation of Italian 150 kV Sub-Transmission Lines

The lightning performance evaluation of overhead lines (OHLs) is a very important task, since the vast majority of line outages are due to backflashover caused by a direct lightning stroke. The paper presents results concerning the lightning performance evaluation of existing Italian 150 kV OHLs. An ATP-EMTP Monte Carlo procedure is used to assess the OHL backflashover rate (BFOR): main feature of the procedure is a simplified pi-circuit model able to simulate the transient grounding system behavior with high accuracy and very low computational effort. In order to improve the OHL lightning performance, countermeasures are proposed and their effectiveness is preliminary evaluated.