This study addresses a 1.8kV bilateral feeding system for DC railway applications, composed of multi-pulse diode rectifiers at both ends and a storage unit with a DC/DC converter located at an intermediate station. The storage system introduces an additional degree of freedom to control power flows by applying a specific voltage at a strategic point between the passive rectifiers. This paper formulates a voltage compensation problem aimed at reinforcing the network while minimizing conduction losses along the catenary. Due to the nonlinear nature of the power balance equations, a closed-form analytical solution is not directly obtained. To overcome this, the paper proposes an approximation method for the pantograph voltage to enable an analytical formulation of the optimization problem. A comparison between the proposed analytical approach and a numerical iterative optimization method is presented and discussed.

DC energy hubs have emerged as suitable candidates to enhance the electrical infrastructure in a localized approach, allowing future expansion in the transportation sector despite the electricity grid congestion. However, a risk in designing such a hub is that the outcome of the optimization can be a mere consequence of the (lack of) sophistication of its generation and load models. In that aim, this paper presents a sensitivity analysis for a power demand profile for a DC railway traction power substation, taking into account traction power parameters and the heating, ventilation, and air conditioning (HVAC) modeling approaches. It is found that the traction parameters such as total mass can be confidently considered using an averaged value. On the other hand, modeling the HVAC system using an averaged power demand can lead to errors over 6%, especially in the recovered braking energy calculations.

The increasing power levels handled by electric vehicle (EV) dc fast chargers will impose additional challenges to the switching devices in order to cope with the efficiency requirements. A cost-effective alternative to achieve highly efficient power conversion is through the partial-power conversion concept. This article validates the advantages of a step-down Type II partial-power converter (PPC), based on the phase-shifted full-bridge converter, for EV fast chargers. By exploiting the reduced voltage range of an EV battery pack along with the reduced power ratio for a Type II PPC, an extremely efficient charging process can be achieved. The concept is validated with the development of a 7-kW demonstrator, and hence, realistic efficiency measurements are obtained. Results indicate the effectiveness of charging a battery by merely handling 13.32% of the power provided to it, with a peak efficiency of 99.11%.

This paper proposes an interleaved partial power converter (PPC) for the DC-DC conversion stage of electric vehicles (EVs) fast charging stations. The proposed converter topology is based on the H-bridge DC-DC converter. PPC allows the converter to process only a fraction of the total power, the rest being bypassed and directly supplied to the load. This increases the converter efficiency, as only a portion of the power goes through the converter, thus increasing its efficiency. The principle of operation of the proposed PPC is theoretically analyzed. Simulations of the behavior of the proposed PPC are provided for the charging of an EV battery. Results show the good behavior of the proposed system. It is in particular verified that the proposed converter only process a fraction of the power around 36% for the entire output power range. Comparison with a classical full power converter is provided showing that the proposed topology leads to a significant improvement in terms of conversion efficiency, from 95.1% to 98.3%.