Development of a regenerative braking energy utilization device for heavy-haul electrified railways

To solve power quality deficiencies in the traction power supply system of heavy-duty electrified railways, such as negative sequences, reactive power, and harmonics, and to make full use of regenerative braking energy, a regenerative braking energy utilization device was developed in this study, with a railroad power conditioner (RPC) capacity of 2 × 5 MVA and an energy storage capacity of 5 MW/350 kWh. The device features a main circuit structure with multi-unit direct parallel connections, which simplifies the transformer winding configuration and reduces the cost of the transformer, leading to an improvement in device availability. For the control of RPC, a "virtual three-phase" control algorithm was proposed to implement negative sequence and reactive power control within the <italic>dq</italic> axis framework. This algorithm sets clear power quality control goals, ensuring better control performance. Finally, the main functions of the proposed system were verified against key indicators obtained using a reciprocal power-fed test platform, demonstrating high performance.