The Impact of the Drainage Cabinet on DC Current Flowing into the Neutral Point of the Power Transformer

To study the impact of the drainage cabinet on the DC current flowing into the neutral point of the power transformer, a simulation model was built using CDEGS. The case study includes one 500kV substation, seven 220kV substations, and a subway system with a total length of 13.5 km and nine traction substations. The potential, primary stray current, and secondary stray current were compared before and after the commissioning of the drainage cabinet. Additionally, the effect of the train's position was analyzed. The results show that after the commissioning of the drainage cabinet, when the train reaches position 23, both the potentials of the grounding grid and the DC current at the substation decrease. The impact of the train's position varies across different substations. In most cases, the DC current decreases after the commissioning of the drainage cabinet.