Integrated Regenerative Braking Energy Utilization System for Multi-Substations in Electrified Railways

This paper proposes an integrated regenerative braking energy utilization system (RBEUS) to improve regenerative braking energy (RBE) utilization in electrified railways. The proposed RBEUS uses a traction substation energy storage system and two sectioning post converters to achieve coordinated RBE utilization in three consecutive traction substations via power-sharing and storage, and the power quality can also be improved. A hierarchically coordinated control strategy is developed based on the operation principle to provide real-time power management and control for the RBEUS. In the system layer, a centralized power management strategy is designed for operation mode management and active power command generation. It uses a sequential quadratic programming-based algorithm to solve the objective function to achieve optimal RBE utilization under different operation modes. In the converter layer, local controllers of the RBEUS enable converters to respond to the active power commands from the system layer and reactive power commands generated by themself for power flow control. The effectiveness of the RBEUS is comprehensively verified by using a hardware-in-the-loop (HIL) experiment. Besides, a comparison analysis of the RBEUS and literature methods is conducted to testify the superiority of the RBEUS. The feasibility of RBEUS implementation is discussed from fault protection and economy.