湖南2008年冰灾引起的倒塔原因分析

Analysis of the Causes of Tower Collapses in Hunan During the 2008 Ice Storm

为分析湖南2008年冰灾引起的倒塔原因,现场调查了2008年湖南冰灾期间≥220kV输电线路的受损情况,发现倒塔线路覆冰厚度主要集中在20～60mm,同时微地形和微气象造成覆冰加重和覆冰的不均匀性,档距、塔形等对线路倒塔也存在影响。分析倒杆断线的形式认为覆冰太厚超过设计值、垂直荷载压垮和不平衡张力拉垮是造成线路倒塔的原因,提出了湖南输电线路抗冰按20mm设计建设最小骨干网架、采用短路融冰等的具体建议,以供杆塔的防冰工作参考。

The damage of the transmission lines in Hunan during the 2008 ice storm is surveyed and the main causes for the tower collapses and line failures are analyzed. It is found that the ice accretion thickness on the failed lines mostly falls in the range of 20-60mm which is well beyond the designed standard. In addition, the situation may be worsened by the nonhomogeneity of the ice accretion due to microtopography and micrometeorology conditions, span distance, and the imbalanced tension caused by vertical load. Based on the study, some detailed suggestions are proposed for design standard of backbone transmission lines in Hunan power grid such as the tolerant standard of 20 mm for ice accretion and short circuit ice melt etc.