计算特高杆塔雷击响应的感应电荷准静法

雷击杆塔引起的过电压是导致输电线路事故的原因之一 ,需要尽量准确估计 ,而特高杆塔系统上传播的雷电波是球面波 ,为避免建立等效电路的困难建立了雷击杆塔、地线、导线系统响应分析的数学模型 ,提出了感应电荷准静法 ,用电磁场理论确定绝缘子串两端电压。分析对位参考点和分流问题后提出了新计算分流系数法。研究发现杆塔电位包括可变的抵消分量和雷电单极电荷引起的恒定分量两部分。感应电荷准静法计算杆塔模型的冲击响应与NEC 2的计算结果基本一致。

Quasi-Steady Induced Charge Method to Calculation of Lightning Performance of ULtra-High Transmission Towers

The overvoltage caused by lightning strike on towers is one of reasons of accidents on transmission lines. It is necessary to evaluate accurately lightning overvoltage on transmission tower, especially for the ultra-high transmission tower system. The lightning wave traveling along UHV tower is spherical wave other than the normal plane wave. A mathematical model of the response of the combination of tower, ground wire, and conductor under struck by lightning is established and a quasi-steady induced charge method is proposed. Electromagnetic field theory is employed to determine the voltage between the two terminals of insulator string. An improved calculation method of current division is proposed after analysis of the point of potential reference and current division. It is found that the potential of the tower system is composed of two components, that are, the variable offset potential and the constant potential caused by unipolar charges of the lightning. The strike response calculated by quasi-steady induced charge method agrees basically with the results calculated by method of NEC-2.