Computing Research For Lightning Protection Of Overhead Distribution Lines

Based on the development of market economic, especially the rising of high-technology, users take more and more attention on electric quality. As an important component part of power system, distribution system is nearer to user. The reliability of distribution power supply have great effect to consumer. Accidents caused by thunder account for 70%～80% of whole circuit trip accidents, especially in some area where the lightning activates strongly and the terrain is very complex and the soil resistance is very high. probability of lightning flashover will be higher, accident of lightning poses a great thread to the safe operation of distribution system.There are three sources of lightning stroke damage in overhead transmission line: straight lightning strike on tower top, round strike or straight strike to conductor and lightning induced surge. In addition, lightning incoming surge along the lines will intrude the power plant and substation after lightning flashover, it brings great menace to many electrical equipments. So based on present situation of overhead transmission line, study and compareson on current regular efforts for lightning protection have very important significance. The study can also provides a reference basis for operation work and design of lightning protection.This paper summarizes the present situation and regular efforts for lightning protection of overhead lines up to 35kV.Based on the general conditions of tower and lines operated at 35kV and 10kV,the paper builds up some simulated calculation models for lightning overvoltage on the transmission lines by means of international universal advanced graphic electromagnetic transient calculation program ATPDraw3.4. The main work of this paper is calculation and theoretical analysis about all practicable efforts(such as installing overhead ground wires,upgrading insulation,improving grounding system of line poles and tower,adding lightning arresters along the line)to protect overhead high voltage transmission line from lightning strike.The paper proves that current regular efforts for lightning protection are still practical and effective,and provides some improving ideas for traditional protective measures.