500kV输电塔线覆冰有限元计算

Finite Element Calculation of 500 kV Iced Power Transmission System

输电塔线体系中铁塔的纵向不平衡张力是危害输电线路安全稳定运行的重要因素之一。为有效计算由档距、高差和不均匀荷载引起的纵向不平衡张力,应用梁单元和索单元建立了输电铁塔和导线整体单元模型。对输电塔线体系结构覆冰荷载进行有限元计算后得到了铁塔的不平衡张力,分析了铁塔的最大压应力随覆冰厚度的变化,指出了档距差和高差角过大是产生不平衡张力的主要原因,而不平衡张力致使铁塔失稳。复沙Ⅰ线500 kV输电线路的实例计算表明该方法非常有效。

EHV transmission system consisting of long span transmission lines and towers is an integrity as a structure, in the process of design, the strength calculation of the conductor and the tower is independent, it is difficult to compute the longitudinal unbalanced tension of the tower. However, the unbalanced tension is one of the important factors impacting the safe running of transmission line, so it has important meaning to accurately compute the longitudinal unbalanced tension caused by span, height difference and uneven load of the transmission line. In this paper, the beam element is used to simulate the transmission tower, and the cable element is used to simulate the transmission line. In this way, the spatial finite element model of the system is established, which is used for structure analyses of the iced transmission system, and the unbalanced tension of the towers is calculated, the maximum compressive stress of the towers are analyzed along with the ice thickness. It is pointed out that great differences of span and angle of height are the main factors which cause unbalanced tension and make tower falling down, however, the tower located at the transmission line with a well-proportioned span and small angle of height difference would still be upright and stable even though the ice load is greater than the design value. The computation results of 500 kV Fusha line I show the finite element method is very effective.