±1 100 kV导线覆冰断线时V串偏移及不平衡张力分析

采用V串伸入塔身布置方案,可缩短±1 100 kV输电铁塔横担长度,降低塔重并减小走廊宽度。覆冰导线断线冲击时的V串偏移量是确定V串伸入塔身布置方案的重要控制因素,准确计算覆冰导线断线动态不平衡张力可为校核线路避雷器的结构强度提供依据。在通用有限元软件ANSYS中建立了±1 100 kV线路连续7档导线-V串体系模型,采用降温法施加导线初始张力,体系阻尼以Rayleigh阻尼形式施加,假定4根覆冰子导线同时发生断裂,通过杀死断线位置的导线单元来实现断线模拟。采用非线性瞬态分析方法,分别计算了考虑子间隔棒影响前后V串偏移量及挂点不平衡张力时程曲线。考虑子间隔棒影响时,覆冰导线V串偏移量和不平衡张力动态峰值,小于设计采用的静态、无子间隔棒模型计算值,即按设计取值确定的V串伸入塔身方案及断线不平衡张力偏于安全。

Analysis on V-String Offset and Unbalanced Tension Forces Under Broken Iced Conductor of ±1 100 kV Transmission Lines

By applying the scheme of stretching the V-string into the tower body, the length of the cross arm of ±1 100 kV transmission tower can be shorten. As a result, the tower weight and the corridor width can be reduced. The V-string offset with broken iced conductors is an important controlling parameter for determining the layout scheme of V-string stretching into the tower body. Accurate calculation of the dynamic unbalanced tension forces of the broken iced conductor can provide the basis for checking the structural strength of the lighting protectors of transmission lines. A seven-span conductor-V-string finite element analysis(FEA) model of ±1 100 kV line section is established with general software ANSYS. The initial tension force of conductors can be applied by lowing temperature method. The damping of the conductor-V-string system is realized by Rayleigh damping form. Four sub-conductors are assumed to be broken simultaneously. The conductor elements at the broken point are killed for realizing the broken conductor simulation. By using nonlinear transient analysing method, the time histories of the V-string offset and the unbalanced tension forces at the suspension point with and without sub-spacers are calculated. When considering the effect of the sub-spacers, the peak values of the V-string offset and the unbalanced tension forces are lower than the design values calculated by static model without sub-spacers. It is safe to determine the scheme of V-string stretching into the tower body and the unbalanced tension forces according to design values.