Analysis of 2 m Level Gap Flashover Characteristics Under Positive Lightning Impulse

Accurate assessment of the lightning resistance performance of transmission lines is of great significance to the safety and economic operation of the power grid. In this study, focusing on the flashover characteristics of 2 m level gaps under lightning impulse, flashover tests were conducted on 220 kV composite insulator and 2 m rod-plate gap at a national engineering laboratory in plain area, using standard and short-tail waveforms. The flashover criteria for 2 m level gaps under lightning strikes were investigated, and the differences of U50% and impulse characteristics between insulators and air gaps under different impulse waveforms were compared and analyzed. Subsequently, based on the real impulse waveforms and the results of flashover tests, preliminary development model parameters suitable for positive standard and short-tail waves were proposed for 2 m level gaps. Finally, the applicabilities of the models were verified by comparing the volt-second characteristics scatter obtained from the tests with the fitted characteristic curves of the leader development models.