基于四阶矩法的输电线路覆冰可靠度分析

The Reliability Analysis of Transmission Line Coated with Icing Based on the Fourth-moment Method

架空导线长期处于复杂环境下,经常遭受覆冰影响。为了保证输电线路的安全运行,架空导线的可靠度分析是十分必要的。以输电线路的导线强度失效为失效边界,选择导线的覆冰厚度和容许应力为基本随机变量建立功能函数。采用简化的四阶矩法计算架空导线的可靠指标,并与一次二阶矩法和基于MATLAB的蒙特卡洛模拟法的结果对比。另外引入功能函数的峰度及偏度到可靠度分析中。结果表明:四阶矩法的功能函数值及可靠指标普遍偏于保守,并且其可靠指标计算的结果相比一次二阶矩法的结果依然可取。因此可将改进的四阶矩法应用于等高悬点输电线路的可靠度计算中。

Overhead wires in complex environment are often subjected to icing problems. In order to ensure the safe operation of the transmission lines,it is necessary to improve the reliability analysis of the overhead wires. Here,the allowable stress of wire and ice thickness were selected as the basic random variables to establish the performance functions of overhead wires. And then the improved fourth-moment method was adopted to calculate the reliable index of transmission lines. The results were compared with those of the second-moment method and Monte Carlo simulation based on MATLAB. In addition,the kurtosis and skewness of the functions were introduced to the reliability analysis. The results indicate that： the function and reliability index of the fourth-moment method are generally conservative,but the calculation result of the reliability index is still preferable compared to that of the second-moment method. Hence,the improved fourth-moment method can be applied to the reliability calculation of transmission lines.