Theoretic And Experimental Study On Lightning Surge Response Of Transmission Towers

Lightning stroke is one of the important reasons that result in power failure. Tower lightning surge response performance is the important factor deciding transmission line lightning over-voltage. There are collective parameter method which is adopted in lightning protection rules, direct measurement method, electromagnetic field method and so on. Collective parameter method is a kind of approximate method after several times of refraction and reflection, which can't reflect the response of wave head and high towers, and the selection of equivalent parameters is approximate; Direct measurement method is limited in application because of inevitable electromagnetic coupling between conductors .In addition, it's impossible to simulate lightning path veritably so that lightning stroke can't reappear, and the measured parameters are not so right. The paper describes the limitation about the above methods and creates mathematic model when lightning is occurring based on electromagnetic analysis. The paper analyzes lightning surge response of generic towers using quasi-steady induced charge method. Quasi-steady induced charge method improves field-cancellation method as the following:The infinite point is taken as potential reference point, instead of the junction of ground wire and tower.Take the geometrical size of ground wire, conductor, tower and their space relationship into consideration, instead of simplified model in which ground wire is parallel to conductor and they are all perpendicular with tower.A series of univocal and concise equations was developed.The paper introduced how to resolve the refraction and reflection coefficients when using quasi-steady induced charge to analyze generic towers, and improved tower lightning stroke response software based on quasi-steady induced charge. In order to validate the correctness of software, two kinds of tower are used in lightning surge response experiment and the results of software and measurement are compared. At the same time, the results of software and lightning protection rules are also compared. The comparison indicates the results of software are believable.