Study On Lightning Protection Performance And Technical And Economical Research For Transmission Lines

Lightning is the important reason of causing the transmission lines faults, improve the line’s lightning protection performance can effectively reduce lightning trip-out rate. In order to guarantee the reliability of power supply, need to take the necessary lightning protection measures, and satisfy the technical and economical requirements of the lightning protection alteration project at the same time.This article first discusses the differences between equivalent inductance models and multi-surge impedance models of towers, establishes 4 kinds of more truthful typical 220kV transmission towers’ Hara multi-surge impedance models. Use ATP-EMTP program to simulate the impact characteristics of the typical towers under the action of lightning current. When lightning strikes the top of the tower, through simulation research, the factors which greatly influence the lightning withstand level are discussed, these factors include grounding resistance, insulation, zinc oxide arrester and coupling ground wire. From improving the lightning withstand level of lines, discusses and analyses the method of improve the level of insulation, the configuration modes of zinc oxide arrester and the height of coupling ground wire. In order to protect transmission lines from shielding failure, except for the common lightning protection measures, Through analyzing the capacity of triggered lightning between lightning rod and grounding wire, sideward rods installed onto the cross arm of towers or sideward needles installed on ground wires’are taken into consideration, the sideward rods or needles can shielding the dangerous area near the tower, calculates out the effective protection distance of sideward rods or needles in different length, proposes the installation strategies of sideward rods or needles that used for protecting 220kV typical transmission lines from shielding failure, according to the existing lightning protection measures, based on the three scales improved AHP, analyses the technical and economical performance of a certain 220kV transmission line’s lightning protection measures, then identify the priorities of the lightning protection alteration measures.The study found that except ’JG’ type tower, the side phase’s back flashover lightning overvoltage of the other 3 kinds of typical towers are higher than the middle phase’s when lightning strikes the top of the tower, reduce the grounding resistance or install zinc oxide arrester can effectively improve the lightning protection performance, increase the pieces of insulator or install couple ground wire can enhance the lightning withstand level in different degrees, calculation shows that the effective protection distance of sideward rods installed onto the cross arm of towers is greater than the effective protection distance of side needles installed on ground wires, to reduce the single-circuit transmission line shielding failure rate, sideward rod installed onto the side phase’s cross arm should be taken into account first, then install several ground wire’s side needles can effectively shielding the dangerous area near the tower. Conclusions are obtained at the end of paper, this certain 220kV transmission line’s lightning protection alteration measures’priorities are as follows:reducing earthing resistance, adding two pieces of insulators for each phase, installing zinc oxide arresters for side phases, erecting coupled earth wire and installing sideward rods or side needles.