Study On Performance And Feasibility Of Lightning Protection Gaps In Yangjiang Distribution Network

Distribution network supply for the customer directly. At the same time, the coverage area of distribution network is large. Therefore, the distribution network is one of the main components which affect the reliability of power system. Because the lightning withstand level of distribution feeders is low, the feeder will be tripped usually caused by the lightning. This decrease the reliability of the power system largely. In recent years, with the rapid economic development of Yangjiang city, industrial, commercial and residential electricity consumption increased significantly, increasing with the distribution line grid structure, the demand of reliability and stability of power system is also improved accordingly.Regional lightning activity in Yangjiang Hailing area is very frequent. Lightning flashover became the main reason for the region distribution line tripping. Due to low lightning withstand level of distribution feeder, lightning easily lead to tripping of the whole feeder easily, even with line break accident. Coupled with the application of cables in urban areas, distribution lines are no longer purely overhead lines. The fault types of feeders become more complex. It has a great adverse effect on the normal operation of Yangjiang grid. Because of the wide coverage area, the traditional lightning protection applied to the distribution feeders need a huge investment, besides the increase of line maintenance. Therefore, seeking a simple and effective lightning protection approach is important for the enhancement of the reliability of power system.In this thesis, the grid structure and insulation coordination of Yangjiang grid are analyzed in detail. Combined with the current situation of lightning in the area, the regional goals of the lightning protection reformation are put forward. With field investigation of the typical feeders, lightning induced voltage average are calculated theoretically. Several distribution network renovation of lightning protections are compared both of the advantages and disadvantages. On this basis, the thesis analyzes the application of two types of lightning protections, and puts forward the use of parallel gap. By considering the neutral point operation mode, insulator type and automatic recloser in the distribution network, the parallel gap is testified as an effective lightning protection for Hailing area. The studying work of the thesis is very useful for the lightning protection for the distribution network of Yangjiang city.