Innovative Protection Measures for Lightning Accidents Occurred in 10 kV Distribution Network of Jinzhai Area

The tripping frequency of 10kV distribution network line in Jinzhai County, caused by lightning accidents, is increasing in recent years. Effective protection measures to reduce the risks of line tripping becomes necessary. In this paper, statistics analyses on the events of lightning fall in Jinzhai area occurred in recent years were made. Damages caused by lightning accidents on distribution network were discussed in terms of distribution of lightning density and distribution of ground lightning intensity. The changing trend of line tripping caused by lightning accidents in recent years was studied, in comparison with the lightning withstand level of distribution network line at present. The results show that in the past three years, the increase of line tripping events is mainly due to the increase of ground lightning density and intensity in Jinzhai area. Lightning protection measures which mount lightning arresters on local poles and towers are confirmed to have limited effects on improving lightning protection performance on the whole 10kV distribution network, an innovative lightning protection scheme is put forward. The scheme could introduce improvement in insulation levels by installing Insulated cross arm in distribution network. The line model is simulated in EMTP. The performances of lightning protection before and after the application of the scheme are compared. The simulation results show that the innovative scheme can effectively improve the lightning resistance level of the entire line system. Following the above simulation results, the threats to the safety of substation operation, caused by the improvement of line insulation level, are further analyzed. The possible solutions for the threats are provided.