Research On Lightning Resistance Performance Of 66kV Double Circuit Transmission Line On The Same Tower

Lightning is a frequent phenomenon in nature,which poses a great threat to the safe operation of power systems,especially overhead transmission lines.With the development of urban economy,the increasing power load makes the land use of transmission line corridor become an important problem to be solved urgently.The operation of Multi-circuit Transmission Lines on the same tower is one of the effective ways to alleviate the land demand of line corridors.The tower height of multi-circuit lines on the same tower is obviously higher than that of single-circuit lines,and the probability of direct lightning damage is relatively high.In order to avoid the phenomenon of multiple simultaneous flashover under the action of high-amplitude lightning current,the requirements for lightning protection are more stringent.In recent years,lightning tripping accidents have occurred on four lines of 66kV double-circuit transmission lines on the same tower,Jinshu line and Chengfeng line in Jilin area.The neutral point of 66kV system is grounded by arc suppression coil.When single-phase flashover occurs,the line does not trip,and because lightning shielding wire may only cause single-phase flashover of the line,the main reason for tripping of these four lines should be lightning direct striking pole tower.At present,researchers focus more on the lightning protection of transmission lines in 110kV and above transmission systems,while little attention is paid to the lightning protection of distribution systems,especially 66kV systems operating only in Northeast China.In order to reproduce the theory of line fault,EMTP model is used to simulate the fault line.The accuracy of the model is proved by comparing with the observation data of lightning location system.In this paper,the influence of tower grounding resistance,tower height,working voltage,lightning induced voltage and conductor alignment phase sequence on line lightning resistance level is analyzed by using this calculation model.The effect of adding lightning arrester on improving line lightning resistance level is investigated by comparing tower top potential,transverse load potential and conductor potential.In addition,by calculating the absorbed energy of the lightning arrester,the lightning resistance level of the line is investigated.The results show that when the lightning current amplitude does not exceed 327 kA,the insulator string with the lightning arrester will not flashover.According to many lightning observation data,the probability of lightning current exceeding 327 kA is 1.76×10^-4n/?km²·a?,and the probability is very low.Therefore,it can be approximated that the conductor equipped with lightning arrester can achieve reliable lightning protection.Considering the lightning protection effect and economy,in order to avoid the waste caused by adding full-phase lightning arresters,the optimal configuration of lightning arresters for 66kV double-circuit transmission lines on the same tower can be achieved by simulation calculation.The simulation results can provide a higher reference value for the operation and maintenance of transmission lines.