Performance of Annual Flashover Rate at Individual Poles in a Distribution Network Due to Indirect Lightning

The complex distribution network has an obviously various lightning performance with that of the straight periodic lines, due to the uneven pole spans and feeder structure in the distribution network. In this paper, the lightning-induced flashover (FO) performance in a distribution network is investigated via a Monte Carlo method, based on the numerical PEEC-MTL method for line modeling and transient simulation. Different from the traditional indicator, i.e., the flashover rate of a total line, the annual FO number at individual poles is defined and concerned to reflect the distribution of the FO risk due to indirect lightning strikes. It is found that the in a part of an existing rural distribution network of concern if the terminal poles with distribution transformers located protected by surge arresters by default, the poles where the open area is around are more likely to have a higher annual FO number. The soil conductivity significantly affects the values of the annual FO number of individual poles, while there is no obvious change in its overall distribution characteristic of the distribution network, which is mainly determined by the line topology. Compared with the case without surge arresters besides the distribution transformers, it indicated the great significance of the protection for terminal poles with distribution transformers. The present work could provide a theoretical basis for differentiated protection against indirect lightning and more factors and conditions would be of concern in the following work.