Analysis Calculation And Design Of Direct Lightning Prevention For 220kV Compact Smart Substation

Direct lightning, inductive lightning, spherical lightning and lightning invasion wave are four forms of lightning. High pressure effect caused by direct lightning could damage the insulation of electrical equipments in substation. High heat effect could lead to fire and explosion. Mechanical effect could break the electrical equipments. Damage caused by direct lightning in the operation and maintenance of substation is particularly serious. In conclusion, direct lightning prevention play an important role in the design of substation.In recent years, the gas insulated switchgear has been more and more widely used in compact smart substation in China. In order to implement intensive management in State Grid Corporation, standardized design of transmission and transformation project has been greatly promoted and modularized design project has been presented. Therefore, the existing 220kV substations are similar in the layout and construction area which makes it possible to select a typical substation design program as an example to analyze. At present, lightning arrester is widely used in direct lightning prevention in substation. There are many kinds of methods to calculate the protection range of direct lightning prevention, and polygon method and rolling sphere method are the most common methods. The former is the calculation method of the electric power regulation, and the latter is reflected in the national standard of building lightning prevention.The paper is organized as follows. Firstly, the methods and situation of direct lightning prevention are described. Secondly, the principle analyses and simulations of polygon method and rolling sphere method are introduced. The change tendencies of different protecting height and different lightning conductor height are then obtained. The comparison and analysis through simulation and calculation could be processed after clarifying the principles of the two methods. The above analyses mainly include the change tendencies of protection radius of single lightning conductor, double equal-height lightning conductors and four equal-height lightning conductors. Accordingly, the advantages and disadvantages of the two methods are summarized. Finally, two most typical layouts of substation are taken as examples; the protections of polygon method and rolling sphere method are analyzed in actual substation in this paper. Considering the application range and reliability, it could be found that the polygon method is more suitable for the application in power system substations, compared with.the rolling sphere method...