The bidirectional converter device (BCD) can replace the traditional diode rectifier unit to both supply traction energy to the system and to recover regenerative braking energy. The operating characteristics of BCDs are controllable, and it is very important to study the impact on system energy saving. This paper is based on the application scheme of BCDs to completely replace diode rectifier units. The operating characteristics of the BCD are introduced, and the energy distribution of the system is analyzed. Taking the total energy consumption of the system as the objective function, a substation voltage optimization strategy is proposed considering the dynamic operation of trains. It can dynamically optimize the ratio of energy utilization through different paths, allocate the power of each substation. Finally, a multi-train scenario is carried out by Matlab. The simulation results prove that the proposed strategy can coordinate the power of each substation and reduce the system losses. The system energy utilization is increased by 1.77% compared to the constant voltage control.