| The operating experiences of10kV distribution lines in Jinshandistrict of Shanghai show that lighting accidents still happen frequently onsuchdistribution lines. It seriously jeopardize the reliability of distributionnetwork and power grid safety, and affects the production and life qualityof ordinary people. Therefore, it has significant meaning to research thelightning protection measures of such lines in Jinshan district consideringthe practice conditions of such distribution lines.Aimed on the lightning trip of10kV distribution lines, analysis showthat the lightning induced voltage is the main cause of flash over ondistribution lines. The generation mechanism of lightning induced voltageson distribution lines are investigated in this paper. It is pointed out thatelectrostatic induction component is the main part in the lightning inducedvoltage. The effects of lightning induced voltage on distribution lines arealso analyzed.The lightning accident investigation of10kV distribution lines inJinshan district indicates that lightning induced over-voltage is still themain reason. The insulation level of10kV distribution line in Jinshandistrict directly affects the lightning withstand level of such lines. Insulated overhead line conductor break accidents still keep as increasing prominentproblem. The existing10kV distribution network operating mode of theneutral grounding can not effectively limit the arc setup rate underlightning strokes. The lightning protection measures for power distributionequipment are also imperfect. Caused by the above-mentioned problems inJinshan district, the situation of lightning protection for10kV distributionline is still serious.Considering the actual situations of10kVdistribution lines, aimed onreducing the line insulation flashover probability, lightning protectionmeasures for insulated overhead lines are employed. Appropriate neutralgrounding mode are considered for reducing the rate of arc setup. Parallelgap and surge arrester united protection measures for10kV distributionlines are also adopted. Besides the above improved lightning protectionmeasures, guidelines for the operation of switch re-closing under differentforms of network structure and operation mode of neutral grounding arealso drafted to improve the lightning protection of10kV distributionequipment. Considering the soil resistivity of Jinshan district area,practical ways of reducing the grounding resistance of distribution linetowers are also carried out. The practices of all these measures effectivelyreduced the10kV distribution line lightning trip-out rate in Jinshan district. |
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