城市电网中地铁杂散电流分布规律及影响因素分析

Analysis of Distribution of Metro Stray Current in Urban Power Grid and Its Influencing Factors

为揭示城市电网中地铁杂散电流的分布规律及其影响因素,该文基于PSCAD/EMTDC仿真平台,结合深圳电网某片区电网的实际拓扑结构及电气参数,建立包含该片区220kV及以上电压等级交流电网的杂散电流分布仿真模型,利用地铁早发车时段内片区电网中变压器中性点直流电流的实测数据对仿真模型进行校验。在此基础上,仿真分析城市电网中地铁杂散电流的分布规律与特征;并分析变压器漏抗、大地电阻率及避雷线的标称面积等因素对城市电网中地铁杂散电流分布的影响。仿真结果表明,当地铁杂散电流入侵城市电网时,输电线路、避雷线及大地中均存在杂散电流,且杂散电流主要通过输电线路进行传播;当变压器漏抗增大时,流向该变压器的杂散电流将减小;当接地变压器附近的大地电阻率变小时,变压器中性点直流电流增加;而避雷线标称面积的改变对地铁杂散电流分布影响微弱。

In order to reveal the distribution and influencing factors of metro stray current in the urban power grid,based on PSCAD/EMTDC electromagnetic simulation platform,this paper establishes the simulation model of the stray current distribution in the urban power grid with 220 kV and above voltage level in this area combined with the actual topology structure and the electrical parameters of the power grid in a certain area of Shenzhen Power Grid.The simulation model simulates the operating conditions of metro at the early departure time,and is verified with the measured data of the neutral point DC of the grounding transformer.It analyzes the stray current distribution characteristics in the urban power grid.In addition,it studies the effects of the transformer leakage reactance,resistivity,and the nominal area of the lightning conductors on the distribution of metro stray current in the urban power grid.The results show that when metro stray current invades the urban power grid,there will be stray current in the transmission lines,the lightning protection lines and the ground,and the stray current will mainly propagate through the transmission lines.When the leakage reactance of the transformer increases,the stray current flowing to the transformer decreases;When the earth resistivity near the grounding transformer decreases,the direct current at neutral point of the transformer increases;The change of the nominal area of the lightning protection line has little influence on the distribution of metro stray current in the power network.