Research On Lightning Protection Technology For Double Circuit Transmission Line On The Same Tower

The development of national economy is closely related to the production of electric power.With the continuous expansion of population density and transmission line construction scale in China,the resources of transmission line corridor are becoming increasingly tight.In order to solve the contradiction between the land use and the land resource shortage of the transmission line corridor,more and more double circuit lines of the same tower and multiple circuit lines are put into operation.Compared with single-circuit transmission lines,multi-circuit transmission lines with the same voltage level are more prone to lightning accidents,which seriously harm the safe operation of the power system.The stability of the local power system is seriously threatened due to the frequent thunderstorms,complex terrain and frequent lightning accidents in the northeast of Heilongjiang Province.In the past few years,many lightning flashover accidents have occurred in Guanghui A and B lines and Xilingji A and B lines.Most of the reasons for the accidents are the counterattack tripping of poles and towers caused by lightning,which has a bad impact on the safe and stable operation of the power system in the region.In this paper,the accident analysis and recurrence of the faults of the 66 k V double circuit transmission lines in the same tower were carried out,and the lightning resistance performance of the region was evaluated.The differentiated lightning protection criteria were adopted and the lightning protection strategy was formulated,which is of great significance to reduce the trip rate of the poles and towers in the region and improve the safe and stable operation of the power system.In this paper,the flashover model of 66 kV transmission line is established by using the electromagnetic transient simulation software.The correctness of the model is verified by the actual accident reoccurrence.On this basis,the influence degree of different factors on the lightning resistance level of the flashover is discussed,and the relationship between the grounding resistance and tower height and the lightning resistance level of the flashover is studied.Calculate the effect of horizontal time interval of counterattack lightning resistance;The lightning resistance level of phase sequence corresponding to several arrangement modes of conductor is analyzed.At the same time,the two lightning protection measures of installing the line lightning arrester and reducing the grounding resistance are analyzed.The lightning protection effect of installing the lightning arrester is analyzed,and the lightning protection safety of the 66 k V double circuit transmission line with the same tower is analyzed through simulation analysis method.Finally,according to the risk assessment results and line faults,the order of differentiated lightning protection transformation is determined,and according to the principle of lightning protection transformation,the lightning protection scheme is formulated for the transmission line and the transformation effect is evaluated.