多回并联电缆线路参数的不对称性分析

Analysis on Asymmetry of Sequence Parameters for Parallel Multi-circuit Cables

输电线路参数的不对称性对电网的安全运行有着重要影响。为分析并联电缆线路参数的不对称性,首先以卡松线路模型为基础,建立电缆序阻抗参数的计算模型,将高压单芯电缆的金属护套视作普通线路,与大地构成"护套-大地"回路,进而推广到多回并联运行的电缆线路,并阐述了多回电缆序阻抗参数的计算方法;然后通过引入线路参数不平衡度的概念,重点对比分析了几种典型相序排列方式下并联双回电缆线路序阻抗参数的不对称性。分析结果表明:双回并联电缆导线"品"字型排列的对称性优于垂直排列和水平排列,其中又以"品"字型垂直排列的对称性最佳。

The asymmetry of parameters of transmission lines has important influence on the security of power system.In order to analyze the asymmetry of parameters of parallel cable,a calculation method of multi-circuit cables based on Carson model is introduced,in which the metal sheath of single-core cables is regarded as a common transmission line and is composed into the＂sheath-earth＂circuit with earth,then the method can be extended to calculate the parallel multi-circuit cables.The concept of unbalance factor of transmission line is described,and the asymmetry of parameters of several typical phase-order arrangements for parallel two-circuit cables is comparatively analyzed.The result of analysis shows that the symmetry of triangle arrangement is better than vertical and horizontal arrangement,in which the vertical triang1earrangement is the best.