地铁杂散电流造成的电网变压器直流偏磁特征量分析

Analysis on the DC Magnetic Bias Characteristic of Transformer in Power System Caused by the Subway Stray Current

地铁杂散电流导致城市电网变压器直流偏磁,威胁变压器及电网系统的安全稳定运行。为解决该问题,研发了变电站杂散电流入侵及主变压器偏磁监控平台。根据监测结果,分析了入侵杂散电流的幅值、分布、流动方向特性,并研究了时间段、地铁运行方式、变电站位置及附近地铁线路数量等因素对主变压器直流偏磁特征量的影响。结果表明,入侵变压器中性点的杂散电流造成的直流偏磁非常严重,且地铁系统与电网间可能存在杂散电流金属性传播路径,需要结合变电站规划选址等,从源头针对性地开展相关防治措施研究。

The stray current generated by the subway could cause DC magnetic bias in the transformers of the urban power system,threatening the safe and stable operation of the transformer and the power system.In order to solve this problem,a platform monitoring the stray current invading the substation and the DC magnetic bias characteristic of the transformer is developed.According to the monitoring result,the characteristics of the amplitude,distribution and flow direction of the intrusive stray current are analyzed,and the influence of the time period,the subway operation mode,the substation location and the number of nearby subway lines on the DC bias characteristic of the transformer are studied.The results show that the stray current through the neutral point of the transformer could cause severe DC magnetic bias problem,and there might be a metallic transmission path for the stray current between the subway system and the power system.Thus,it is necessary to carry out targeted research on relevant prevention measures from the source in conjunction with the planning and site selection of the substation.