Study On Transmission Line Lightning Risk Assessment Methods Based On Improved Lightning Trip-out Rate Calculation

With the modern society rapid development of high voltage transmissiontechnology, corridor width, tower height and so on are increased with the increase oftransmission line voltage grade, the possibility of line lightning strike might be moreand more big, thunder and lightning disasters caused economic losses and casualties aremore serious. Therefore, research on area lightning activity and accurately assesslightning resisting performance of transmission line, then put forward reasonablelightning protection measures in order to reduce the loss caused by lightning strikeaccident and the cost of transmission line lightning protection is an urgent problem to besolved.In this paper, the lightning activities and transmission line lightning protectionperformance are studied, the transmission line lightning risk assessment model andevaluation parameter system are put forward,, transmission line lightning riskassessment model is established on the basis of considering all kinds of risk index,realize differentiation lightning risk assessment of the line. The main work is as follows:①In this paper, from tower to tower section type hierarchy evaluation structure oftransmission line is proposed and the risk assessment parameters system consists oflightning trip-out rate, lightning trip-out risks, risks, risks of transmission line lightningfailures four parts is established.②Starting from the actual lightning activity, screen from the lightning locationsystem monitoring data in a given area, use data analysis software fitting to thelightning current amplitude probability distribution function and density of GDP model.Find our the physical contact and relationship between tower detour lightning resistinglevel, against lightning resisting level and tower resisting level by analyzing the factorsthat influence the tower lightning resisting level. On the basis of analysis of the towerlightning resisting level and lightning parameters distribution, the improved lighringtrip-out rate calculation method is presented. The lightning trip-out rate calculatedresults are closer to the actual statistics.③Tower as the basic unit of the transmission line lightning risk assessment,evaluate each part tower lightning tripping risk by comprehensively consideringtopography and climate conditions in transmission line area. Use the improved analytichierarchy process (IAHP) to determine the lightning tripping risk weighting of the tower section, then transmission line risk assessment model is established. Then, rank thetower section lightning tripping risk which can be used to determine the weak towersection of transmission line.④Lightning risk assessment results of three110kV、220kV、500kV transmissionlines show that this method is more accurate than the risk evaluation method which onlyusing transmission line lightning trip-out rate as the evaluation index. This method canrealize the risk assessment from the tower, tower sections to the whole transmission linewhich has stronger applicability.