Fuzzy Logic Control Strategy of Substation Voltage in Urban Rail Flexible Traction Power Supply System

The flexible traction power supply system (FTPSS) for urban rail adopts fully controlled voltage source converter (VSC) to replace the diode rectifier unit, which has the advantages of improving the power supply quality and controlling the DC voltage. However, the impact of VSC DC voltage variations on the performance of FTPSS is not fully understood. This paper established the AC/DC decoupling model of FTPSS and analyzed the different utilization paths of regenerative braking energy. On this basis, the relationship between droop slope and power flow is analyzed by simulation under different power and distance between trains. Subsequently, based on fuzzy logic control (FLC), an adaptive adjustment strategy of substation voltage considering the dynamic operation process of trains is proposed. This strategy actively cooperates with the energy distribution of each station by changing the droop slope, so as to reduce the energy provided by the urban power grid (Eacgridrec) and stabilize the network voltage. Finally, a simulation verification is carried out by a subway line, and the results show that compared with the constant voltage control, the proposed strategy can reduce the Eacgridrec by 5.57%, and reduce the voltage fluctuation by 156.5826V compared to the droop control.