贵州电网老旧输电线路覆冰危险点杆塔结构可靠性分析

Reliability Analysis of Tower Structure at Dangerous Icing Point of Old Transmission Line in Guizhou Power Grid

为了解贵州电网老旧输电线路覆冰危险点杆塔结构可靠性,采用理论研究的方法分析了三种型号输电导线在不同覆冰厚度下的水平荷载与垂直荷载;同时分析了10mm冰区和20mm冰区杆塔在同种档距下不同覆冰厚度;相同覆冰厚度下不同档距和不同高差下导线的不平衡张力。选取220kV典型铁塔YJ22和500kV典型铁塔JG22为代表建立线性三维模型,采用有限元分析的方法研究了正常使用状态和极限承载力状态下两种铁塔的杆件应力情况。结果表明输电线路导线截面越小,覆冰引起的不平衡张力相对变化越大;覆冰造成的不平衡张力随着档距和高差的增加而增大;新规程下老旧输电线路典型铁塔YJ22和JG22在运行时存在较大的安全风险,后续使用时应采取相应加固补强措施提高老旧线路的安全运行能力。

In order to understand the structural reliability of old transmission lines in Guizhou power grid,the horizontal and vertical loads of three types of transmission conductors under different icing thickness are analyzed by theoretical research method.At the same time,the unbalanced tension of conductors in 10mm and 20mm ice area is analyzed under the same span,different icing thickness.Unbalanced tension of conductor under different span and height difference under the same icing thickness are analyzed.Taking 220kV typical tower YJ22 and 500kV typical tower JG22 as representatives,the linear three-dimensional model is established,and the member stress of the two towers under normal service state and ultimate bearing capacity state is studied by finite element analysis.The results show that the smaller the section of conductor and ground wire of transmission line,the greater the relative change of unbalanced tension caused by icing;and the unbalanced tension caused by icing increases with the increase of span and height difference.Under the new regulations,the typical towers YJ22 and JG22 of old transmission lines have great safety risks during operation,corresponding reinforcement measures shall be taken during subsequent use to improve the safe operation capacity of old lines.