Evaluation of Voltage Quality and Energy Saving Benefits of Urban Rail Transit Power Supply Systems Considering the Access of Photovoltaics

Along the route of urban rail transit (URT), the subway depots, parking lots, and elevated subway stations are equipped with sufficient photovoltaic (PV) generation conditions. The access of PVs in the URT power supply system should not only make full use of nearby renewable energy, but also improve the economic operation of the system. In order to quantify the impact of PV access on the URT power supply system, this paper proposes a method to evaluate the voltage quality and energy saving benefits of the URT power supply system, considering PV access. First, by fully considering the random fluctuations of PV output power, as well as the intermittency and impact of traction load, the URT power supply system with PV access is modeled. Then, such values as system voltage and power are calculated through the hybrid AC/DC load flow calculation method. Combined with the results of the load flow calculation, the indicators describing voltage quality and power saving benefits of the system are proposed to quantify the influence of PV access on the system. Finally, a case study concerning a certain section of a subway line is presented to verify the proposed method. It shows that the proposed method can effectively quantify the voltage quality and power saving benefits of the system after PV access, providing valuable insights for design and maintenance personnel to comprehend system state and operating characteristics.