Environmental and Power Quality Assessment of Railway Traction Power Substations

The electrified railways are powered by dedicated traction power substations (TPSSs) that represent non-linear loads for the utility supplying network. Power Quality (PQ) problems affect both the three-phase network that feeds the TPSS, and the contact line itself that completes the traction system. The presence of harmonics can reduce the power factor (PF), by 1-5%, seen by the power system at the primary side of the TPSS. This study focuses on low-order harmonics (LOH) due to the AC/DC rectifier for a traditional 3-kV TPSS, through Simulink simulations. Two different scenarios are considered, displaying the trend of the electrical quantities and the PQ of the power flows is verified in the two working conditions. Finally, an environmental evaluation is carried out starting from the obtained results, considering the Italian electricity generation mix and evaluating the amount of Greenhouse Gas (GHG) emitted during the use phase in the two working scenarios.