A Low-cost Scheme for Regenerative Braking Energy Recycling and Negative Sequence Current Compensation of the electrified railway

To ease the increasing electrical energy demand, reduce the operation cost, and improve the power quality of the electrified railway, a low-cost scheme is proposed for recycling the regenerative braking energy and compensating the negative sequence current (NSC). The hardware part of this scheme consists of two three-winding transformers, a railway power conditioner (RPC), a bidirectional DC-DC converter, an energy storage system (ESS), four sets of thyristor-switched capacitors (TSCs) and four sets of thyristor-controlled reactors (TCRs). In this paper, firstly, the structure and working principle of the proposed scheme are introduced, and the device capacity of the RPC for the reactive power compensation is analyzed. Then, the control strategy of each component is designed. Finally, the simulation results are presented to demonstrate that the proposed scheme can not only effectively utilize the regenerative braking energy, but also economically solve the power quality problem.