特高压双回直流架空线路电晕起始电压的计算分析

Calculation and Analysis on Corona Onset Voltage of Double-Circuit UHVDC Overhead Transmission Lines

为研究特高压双回直流架空线路的电晕起始特性,本文考虑线路排列方式和绞线的实际结构,结合气体放电理论建立了特高压双回直流线路的起晕电压计算模型。根据正负极起晕的不同机理,在利用优化模拟电荷法对绞线表面空间电场求解的基础上,计算了各极子导线的起晕电压。分析并讨论了导线布置、温度与气压及绞线参数等因素对起晕电压的影响。计算结果表明:-+/-+排列方式时线路起晕电压值较高。另外,导线半径的增大、气压的升高、分裂数的增加都能显著提高起晕电压。导线对地高度、极间距、上下层导线高度及分裂间距也都会不同程度影响起晕电压。绞线绞入率逼近于0时,绞线起晕电压接近光滑导线的起晕电压。

To study the characteristics of corona onset voltage of double-circuit UHVDC overhead transmission lines,a computation model is established in this paper based on the gas discharge theory and with consideration of the power line＇ s arrangement and the stranded conductor＇ s actual structure.According to the different mechanism of positive and negative corona onset,the corona onset voltages of each pole＇ s sub-conductor are calculated on the basis of solving the surface space electric field of stranded conductor by using the optimized charge simulation method.The impacts of the line arrangement,air temperature,air pressure and parameters of stranded conductors on corona onset voltage are analyzed and discussed.The results show that the value of corona onset voltage is much higher for the-＋/-＋ line arrangement.In addition,the increase of conductor radius,air pressure and bundle number can significantly raise the corona onset voltage.The height of line to ground,anode-cathode distance,the height difference between upper line to lower line and the bundle spacing can also affect the corona onset voltages to varying degrees.When the stranding ratio of the stranded conductor is close to zero,the corresponding corona onset voltage will also be close to the one of the smooth conductor.