Voltage Oriented Control of an Innovative Bidirectional 3 kV Railway electric substation using Parallel Three-Level NPC Converters

Italian railway system is based on 3 kV DC voltage and it is connected to the AC grid through electric substation which are realized with diode rectifier. This configuration does not allow power reversible operation and regenerative braking is not possible with a consequent waste of electric energy which is dissipated on braking rheostats. The present paper proposes a bidirectional electric substation configuration based on NPC parallel connected converter. A control strategy is proposed and simulation results are presented.