Control of metro-trains equipped with onboard supercapacitors for energy saving and reduction of power peak demand

New generation of rapid transit trains requires a more effective energy management for the reduction of energy consumption during the journey. Rapid transit trains can benefit substantially form aboard electric storage devices for the recuperation of the kinetic energy during braking and the limitation of power supplier current during acceleration. This paper proposes a control strategy for aboard supercapacitors integrated with motor drive control. The voltage and current references for supercapacitors are related to the actual train speed and calculated on the basis of train inertial forces and supercapacitors state of charge. The proposed control strategy is very useful for obtaining good performances also with not pre-defined speed cycles. Therefore, the control strategy has been verified on a generic traction cycle via numerical simulations and experimental tests, made on an expressly built electromechanical simulator. The results obtained point out that the proposed control is capable of achieving energy saving and reducing considerably the voltage surge at the overhead contact line during train braking. (C) 2012 Elsevier Ltd. All rights reserved.