RBE Utilization Improvement and Negative Sequence Compensation for Multiunit Energy Router in Railway Hub

A railway hub, formed by the interconnection of mainline railways and urban railway, exhibits the characteristics of high energy consumption, high peak power demand, and abundant regenerative braking energy (RBE). Owing to constraints in power flow path, the hub’s traction substations face challenges, including negative sequence (NS) and low utilization rates of RBE. This study proposes a multiunit energy router (MUER), comprising ac-dc converters, dc-dc converters, an energy storage system (ESS), and adaptive impedance. The MUER functions both as an energy dispatch center and compensation device bridging ac and dc traction power supply systems. By integrating adaptive impedance, the capacity requirements for ac-dc converters are reduced. Consequently, a collaborative control strategy with three-layer structure is developed. In the upper layer, an energy management algorithm is designed for RBE utilization, peak clipping, and valley filling to calculate the total power demand. In the middle layer, based on dynamic reactive power matching of adaptive impedance, the power of converters is coordinated while meeting NS constraint, minimum compensation capacity of ac-dc converters, and the total power demand. The converter control is implemented in the lower control layer. Finally, the experimental results demonstrate that the MUER significantly enhances RBE utilization and NS compensation.