金属路径对电网中地铁杂散电流分布的影响研究

Study on the Effect of the Metal Path on the Distribution of Metro Stray Currents in the Power Grid

随着城市轨道交通快速发展,其带来的电力变压器直流偏磁问题愈发严重。地铁杂散电流逐渐成为城市地区变压器直流偏磁的主要原因。相关设计标准和监测结果表明,地铁与电网的接地系统间存在一条金属连接路径,且该路径可能是影响杂散电流幅值的主要因素之一,但是这条路径很少被现有研究所考虑,其作用影响程度尚不明晰。因此,为了分析杂散电流入侵电网的影响因素,探究不同路径对杂散电流幅值的影响,搭建了地铁与电网的耦合仿真模型,通过与大地介质这一传播路径的电流幅值影响进行对比,定量分析了电缆铠装金属路径对电网中杂散电流的影响程度,发现当地铁与电网间存在金属连接时,杂散电流的分布受到显著影响,入侵电力系统的杂散电流幅值提高了9倍。研究结果表明两系统间的接地网的电缆铠装连接为杂散电流入侵电网提供了良好的导电路径。

With the rapid development of urban rail transit,the direct current(DC)bias problem of power transformers brought by it has become more and more serious.Metro stray currents gradually become the main cause of DC bias magnetization of transformers in urban areas.Relevant design standards and monitoring results indicate that a metallic connection path exists between the grounding system of the metro and power grid,and this path may be one of the main factors affecting the stray current amplitude in the power grid.However,the path is rarely considered by existing studies and its effect on stray currents is unclear.Therefore,in order to analyze the influencing factors of stray currents invading the power grid and explore the influence of different path on the amplitude of stray currents,a coupling simulation model of metro and power grid is built,by comparing the effect of current amplitude with that of the earth medium as a propagation path,the degree of influence of the cable armored metal path is quantitatively analyzed,and it is found that the distribution of stray currents is significantly affected when a metal connection existed between the metro and the power grid,and the stray current amplitude of the intrusion power grid system is increased by 9 times.The research results show that the cable armor connection between grounding grids of two systems provide the good conductive paths for stray currents to invade the power grid.