Dynamic stray current evaluation model of metro system considering reversible DC traction power system

Stray current of DC metro system will accelerate metal corrosion. Therefore, it is necessary to evaluate it. With the application of inverter feedback devices in recent years, stray current is more complex due to the DC traction power system is reversible. To evaluate stray current more accurately, the dynamic evaluation model is proposed in this paper. Firstly, traction power substation (TPS) is equivalent to controlled source, considering the diverse operating characteristics. Based on this, the dynamic evaluation model is built with multiple trains running and TPSs operation. Then, considering the nonlinear and multivalued function characteristics of TPS, the solution method is proposed. The problem of slow convergence or even non-convergence in the stray current solving process of the metro system considering reversible DC traction power system is solved. The model is validated by the field test data. Finally, the model is used to obtain dynamic stray current. Result shows that stray current level tends to be higher as traction trains and braking trains run separately and concentratedly in different areas of the line.