高压单芯电缆线路入地电流分流系数研究

电力工程接地设计时,为使接触电势满足规范要求,一般要考虑架空地线分流影响,尽量降低入地电流大小,从而降低地网电位升。现有接地设计规范提供配电装置采用架空线路出线时的架空地线分流系数计算公式,但对于高压电缆线路出线,电缆金属护层的入地电流分流系数未提供计算依据。本文基于某项目400 kV电缆线路,对电缆金属护层的入地电流分流系数采用解析计算和仿真分析作对比计算,并将推广到一般工程情况。结果可见高压电缆金属护层分流效应相比架空地线更明显,对降低接地计算入地电流有良好效果。

Research on Calculation of Ground Current Ratio of High-voltage Single-core Cable Line

In the design of power engineering grounding,in order to make the contact potential meet the specification requirements,the shunt effect of overhead ground wire should be considered in the grounding design of power engineering,and the grounding current should be reduced as much as possible,so as to reduce the potential rise of grounding grid.Existing related grounding design codes provide the formula for calculating the shunt coefficient of the ground wire when the substation outgoing lines use overhead conductors.However,for high-voltage cable lines,shunt coefficient of the ground current after a portion of the current has passed through the cable's metal sheath is not mentioned.In this paper,based on a project of 400 kV cable line the shunting coefficient is compared with analytical calculation and simulation analysis.After the parameter value range is extended to the general project situation,the results show that the shunting effect of the metal sheath of the high-voltage cable is obvious than that of overhead line,and it has a good effect on reducing the calculation of ground current.