城轨杂散电流在电网系统中的分布特性仿真分析

Simulation Analysis of Distribution Characteristics of Urban Rail Transit Stray Current in Power System

城市轨道交通产生的杂散电流会导致位于地铁密集区域的变压器发生直流偏磁问题,威胁变压器及交流电网系统的安全稳定运行。为解决该问题,建立了地铁杂散电流静态分布模型、深圳地区多层分块土壤模型以及深圳交流电网仿真模型,计算分析了杂散电流引起的交流电网变电站地电位变化及变压器中性点直流电流的分布特性。结果表明,地电位变化及变压器中性点直流电流变化均与地铁运行工况相关,变电站与地铁密集区域间的距离及土壤电阻率是主要影响因素。针对自耦变压器,结合试验测试结果,指出仅在直流超标站点安装电容隔直装置无法消除这类直流偏磁问题,需要从整个区域电网的角度合理配置隔直装置。

The stray current generated by the massive operation of subway transit will affect nearby power transformers by DC bias,threaten the safe and stable operation of transformers and AC grid systems.In order to solve such problems,the static distribution model of subway stray current,the multi-layer block soil model of Shenzhen and the simulation model of Shenzhen AC power grid are established for simulation analysis.The variation of the ground potential of the AC power grid substation and the distribution characteristics of the neutral point DC current of the transformer caused by the stray current are calculated and analyzed.The results show that the change of ground potential and DC current through transformer neutral point is related to the operating conditions of the subway.The distance between the substation and the dense area of the subway line and soil resistivity are the main influencing factors.For the autotransformer,combined with test results,it is pointed out that the installation of the capacitive blocking device at only the DC over-standard site cannot eliminate such DC magnetic bias problems,and it is necessary to properly arrange the blocking device from the perspective of the entire regional power grid.