Lightning Protection Research Of Transmission Line And Substation Based On Flashover Criterion By Leader

The lightning strike is a major threat to the safe operation of the transmission lines, it’s notonly the main cause for the transmission line faults, but also the invasion of the lightning waveleads to damage to the electrical equipments in the substation. So the accuracy of transmissionline calculation model has important academic significance and practical engineering value fortransmission line and substation lightning protection research.In the study of transmission line lightning performance, according to certain flashovercriterion, insulator string flashover is judged by analyzing and comparing the insulator stringvoltage, then get the lightning withstand level, so as the criterion of insulator string flashoverdirectly affects the accuracy of line lightning withstand level. According to the dischargemechanism of long air-gaps, the model of insulator string flashover, integrating the features ofinsulator string, is established in this paper based on the continuous leader progress method.Adopting this method can get the insulator string’s V-t characteristic curve and verify themodel’s accuracy compared with actual measurement data. Based on ATP-EMTP, taking500kVline as an example, and considering the impulse corona effect in the lightning wave, the paperbuilds the lead flashover model considering impulse corona, and computes the lightningwithstand level by different methods of flashover criterion and analyses the veracity andapplicability of these methods based on the operating experience of high voltage transmissionline at home and aboard. Furthermore, the influences of lightning withstand level that worked bydifferent insulator, power frequency voltage phase angle and grounding resistance was studied.The simulation results show that the criterion of insulator flashover based on continuous leadermethod introduced in this paper perform better than the traditional leader flashover criterionwhich just considerate the length of insulator string but ignore the structure.The Lightning Intruding Over-voltage in substation is closely related with flashover situationof insulator, consequently, based on ATP-EMTP, a lightning over-voltage simulation modelcombining500kV substation with incoming lines was established, and the effect of insulatorflashover criterion on Lightning Intruding Over-voltage in substation was researched. Moreover,the insulation coordination of transformer substation when taking the leader flashover criteriathat consistent more with the actual operation of line was checked. The simulation results showthat lightning over-voltage on substation equipment increased when insulator used leaderflashover criterion. From the substation within1.5km,substation equipment may be threatened;from the substation1.5km or more, by reason of attenuation and aberration of lightning wave inpropagation, substation equipment don’t be threatened by invading wave. In order to ensure the safe operation of substation, the lightning prevention measures should be strengthen.