The Research On Lightning Protection Of 110kV Transmission Lines In Guizhou

The city of Duyun, Guizhou province, due to its mountainous and hilly features, is frequently visited by lightening with an average annual fre-quency at 60 days or so. In recent years, 110kv transmission lines trip-off accidents caused by lightening in this city seriously jeopardized the reli-ability of transmission network and power grid safety, which has brought negative impact on people's production activitis and access to electricity. Therefore, the theme of this thesis is to conduct a comprehensive and sys-tematic research on the causes of high frequency of trip-off accidents of 110kv transmission line in this area and find out practical ligntening pre-vention measures, so as to effectively reduce such accidents. Thus, the study ligntening prevention measures are of great significance and have application value to the design and maintenance of electricity transmission and distribution.In order to conduct a detailed analysis on the causes of high occurrence of lightening accidents of 110kv transmission line in Duyun city, the author of this thesis analyzed an abundant materials concerning the operatioinal status of its transmission line, various kinds of parameters such line span, line insulation level, etc. and carried out research and experiment on the spot where 110kv transmission line is located so as to get familiar with the situation there, namely, erection of lightening conductors, tower passed topography, tower grounding resistance and soil resistivity. The author also made a theoretical analysis on both direct and indirect lightning strike phenomenon and conducted lightening arrester computer simulation by employing ATP-EMTP procedure. By establishing lightening strike model, the thesis points out lightening strike is related with ground facilities, to-pography, geological structure and local microclimate, demonstrating that there is an alternation in lightening strike. The thesis summerizes the in-adequacy of lightening prevention measures in easy-hit areas of 110kv transmission line in Duyun city and put forward specific lightening pre-vention measures for those transmission lines that has already under op-eration by analyzing those factors, including easy-hit segments, grounding resistance, insulation level , coupled ground, line arrester, which has brought great influences on lightning withstand level.By carrying out research, the author improved a series of protective measures on 110kv transmission line against lightening strike by lowering tower grounding resistance, establishing coupled ground at easy-hit seg-ment, strengthening insulation level at easy-hit areas, installing side lightening rod on the tower frequently visited by indirected lightening strike, building line Arrester on the tower with relatively high altitude, employing parallel protection gap and minimizing the angle of protection of lightening line.