Model Construction and Analysis of Transformer DC Magnetic Bias Induced by Rail Transit Stray Current

In this paper, transformer DC magnetic bias caused by rail transit stray current is researched. The logic relation and core elements of stray current and DC magnetic bias are analyzed. The mathematics model is instituted through the data from subway operation and power grid monitoring. This model can not only be used for the assessment and treatment of transformer DC magnetic bias, but also can be used to locate the weak points of train track insulation. At the same time, this paper provides a combined stray current control scheme for two different systems of power grid and urban rail transit, which have been achieved remarkable results in Changsha area.