A Unified Model of DC Traction Power Supply System and Stray Current Dissipation

The problem of dc interference caused by stray currents in dc traction power supply system (DPS) is becoming increasingly serious. In order to study the interference degree of stray currents, a unified model of DPS and stray current dissipation based on the direct boundary element method (UBEM) has been established. The stray current collection network (SCCN) polarization potential is an important index to evaluate the leakage level of stray current. In this article, the relationship between SCCN polarization potential and rail-to-earth resistance (RE), train headways and longitudinal resistance of SCCN is investigated. It provides a partial theoretical basis and calculation method for stray current protection and system optimization. Field tests and CDEGS software simulations prove that UBEM is effective. The results show that UBEM is within 6.07% of the CDEGS simulation results and within 11.45% of the field test results. Taking the actual metro project in China as an example, SCCN polarization potential is only affected by local stray current. When RE>7.35 Ω·km, The average value of the SCCN polarization potential drops below 0.5 V.