架空与埋地线缆系统大地返回阻抗和导纳计算方法

Earth Return Impedance and Admittance of Overhead Line-underground Cable Systems

架空导线、埋地电缆、地下金属管线等线缆系统的阻抗和导纳参数是线缆系统内部及系统间过电压防护和电磁兼容性研究的重要参数。该文将大地视为水平分层结构,基于水平方向电偶极子的赫兹矢量方程,利用媒质分界面条件和边界条件,导出大地水平分层时架空与埋地线缆系统大地返回阻抗的递推计算公式,该公式通用性强,适用范围广。此外,还给出了大地任意水平分层时埋地导体系统大地返回导纳的求解方法,以及将大地视为均匀媒质和2层媒质时埋地导体系统大地返回导纳的计算公式。通过与现有文献的计算公式进行对比分析,验证了所提计算方法的正确性和有效性。

The impedance and admittance parameters of multiconductor systems consisting of overhead lines,underground cables and pipelines and so on are of particular importance for the study on overvoltage protection and electromagnetic compatibility within and between systems.In this paper,considering the earth as horizontal layered model,based on the Hertz vector equations of horizontal electric dipole,the recursive formulas of earth return impedance of overhead and underground multiconductor systems are derived by means of the interface conditions and boundary conditions of electric field and magnetic field,which are of high universality and wide application.In addition,the solution to earth return admittances of underground conductor systems is presented in the case of multilayer earth model,along with the formulas of earth return admittances for homogeneous and two-layer earth.Compared with the formulas in the existing literatures,the proposed method is demonstrated to be correct and effective.