Research On Lightning Characteirstics And Its Protective Measures In220kv Gechen Line Of Three Gorges Area

As an indispensable part of the information age,the transmission lines is a powertransmission "blood" that ensure the normal operation of whole society, and it hasdetermine the safety and reliable directly in safe operation of the power grid. The threegorges area is located in western Hubei province, central China area, which undertakeimportant task that transmit the electricity from East areas to western China. However,the lightning trip-out accident is very frequently in this area, among them with220kVGeChen line most serious that has caused the great threat for the power system toreliable operation. Therefore, how to strengthen the lightning protection measures andto ensure the normal operation of the GeChen line is imminent.Differentiation technology and strategy of lightning protection for transmissionlines is a kind of new type, efficient lightning protection measures, which is presentedby state grid corporation of China (SGCC) in2008. This method main basis on somedifferences between the temporal and spatial distribution of lightning, tower structure,and geomorphology features etc, get an accurate assessment of the lightning protectionlevel of transmission line, and finally reach the purposes of reasonable and effectivelightning protection. Therefore, implement the differentiation technology and strategyof lightning protection of GeChen, the first to clear lightning activity characteristic oflines corridor ears, the correlations between thunder characteristic parameters andlightning trip-out accident, the structure characteristic of tower, then presentcorresponding strategy of lightning protection for transmission lines by the resultsIn this paper, the main research results include:(1)Analysis The difference of lightning activity characteristic in GeChen linecorridor area. According to the lightning preventing standard provide by "exchangeelectrical devices overvoltage protection and insulation coordination"(DL/T6201997),in this paper, the lightning activities of lines corridor ears are studied by grid method.Results show that lightning are seasonal cycle change, negative cloud to ground flashesbe more, and19:00~20:00cloud to ground flashes reaches a maximum. Besides,Lightning current probability amplitude accumulated obeys distribution rule with indexfunction.(2)The lightning trip-out accidents are affected by lightning density and Lightningcurrent amplitude. The results of the study show that the13times lightning trip-outaccidents in2000~2009year, occurs at the area of lightning density is more than4times/100km2/year accounted for69.2%; and the change characteristics of lightning trip-outaccidents rate is similar with Lightning current amplitude year by year.(3)by comparing the during or after result of lightning protection, the lightning risklevels is considerably reduced of towers, but the lightning failure rate are still high,according to the lightning preventing standard provide by "the safe operating oftransmission line". (4)The results of the study show that reducing the ground resistance of pole andtower, adding line lightning arrester and using unbalanced insulation protection is moresuitable for improvement of lightning protection220kV GeChen Power TransmissionLine. This paper studies the lightning activity characteristic of regional corridor, thestructural characteristics of tower along GeChen line, the different features of anylightning protection, and finally makes the comprehensive evaluation of lightningresisting level of the tower along the GeChen line. The results show that reducing theground resistance of pole and tower, adding line lightning arrester and using unbalancedinsulation protection is more suitable for improvement of lightning protection. Finally,this article also cited two examples to detailed instructions improvement of lightningprotection of220Kv GeChen line.Comprehensive research results, In order to avoid unnecessary waste of resources,ensure the feasibility and effectiveness of the lightning protection. Should be set up onthe basis of differentiation technology and strategy of lightning protection fortransmission lines, when improvement of lightning protection220kV GeChen PowerTransmission Line. Ultimately improve the lightning impulse withstand level and toreduce lightning trip-out rate of transmission line.