Infinitesimal Method Based Calculation of Metro Stray Current in Multiple Power Supply Sections

The calculation of rail potential and stray current in the DC traction power system can guide the protection against the rail overvoltage problem and mitigate the electrolytic corrosion due to stray current. To obtain the accurate stray current distribution, the infinitesimal method based calculation of metro stray current in multiple power supply sections (PPSs) is studied in this paper. The through-type structure characteristics of power supply system and that of return current system which is constituted of rails - stray current collection mats - tunnel reinforcements - ground (RSTG) are considered in the proposed calculation method. In the traction power supply system, the currents injected into the rail by train, and absorbed by traction power substation (TPS) or regeneratively braking train, are solved by the power flow calculation which considers stray current. In the return current system, these currents are used as the boundary conditions for stray current calculation. Then the rail potential and stray current in multiple PPSs are solved by the infinitesimal method. The verification result shows that the proposed calculation method can effectively calculate the rail potential and stray current in multiple metro PPSs. At last, the novel calculation method is used to gain the dynamic stray current along the metro line and evaluate the influence factors of stray current.