Stdudies The Lightning Protection On 35kV Power System Of Qingzhen Guizhou

The 35kV system is the main power system of Guiyang South Qingzhen power supply bureau. Since it's load is onerous and significant, a critical requirement in lightning shielding performance must be fulfilled and it is necessary to research on new technology and measure to enhance the lightning shielding performance of 35kV system. The lightning shielding situation is very crucial for the following reasons. Firstly, the line corridor of the 35kV system is in mountain areas with complicated terrain, high earth resistivity and dense lightning activities. Secondly, the single transmission line with no transposition, no arc suppress coil and no overhead ground wire following guidelines on 35KV system carries the weight of power supply by itself. At last, after years of ageing, line surge arresters located on input section can not perform correctly and insulator series are in disrepair.In this paper, lightning shielding performance of substations and transmission line of Guiyang South Qingzhen power supply bureau was analysed based on years' operation data. Thorough analysis was made on 35kV Weixin transmission line in consideration of factors such as transmission line corridor terrain, impulse tower resistance, tower space and type, etc. Numerical model of lightning strike tower for calculation was established and a lot of calculation on lightning shielding level.The total research presented in this paper can be found in the following list:(1)Lightning shielding research on 35kV system substations of Guiyang South Qingzhen power supply bureau was completed. Special attention was paid to calculation on the magnitude, gradient and influence of invasion surge. It is found that the system capacity is small that the use of line surge arrest on the head of the input section wound be suitable.(2)The author analysed the lightning shielding performance of typical transmission line, and calculated that of the whole line following the guideline proposed method to locate the weak point.(3)Simulation adopted the high accurate arithmetic was made on the section which is apt to be stroke of the 35kV Weixin transmission line. Reasonable suggestions of installing selectively line surge arrester was proposed.(4)To the condition that most of the 35kV transmission lines are overhead lines, we tabled the proposal of using arc suppress coil to reduce the lightning failure rate anddiscussed the operation modes of the coil. Results of simulation and calculation indicate that the neutral point should be insulated to ground under normal situations while it should be grounded through resonance impedance when single phase grounding failure occurs.Reconstruction of the 35kV transmission line was made following the research results in this paper. Some of the details were installing line arrester on lightning susceptive towers, using tower down lead to ground directly and to avoid unsound grounding and adding conductive cement to tower base and grounding electrode. These new measures enhanced the lightning shielding ability to a certain extent and the effect was proved by the reduction of lightning failure rate in the passed year.