Optimization of Energy-Saving Operation Strategy for On-Board Energy Storage Trains

The implementation of on-board energy storage (OBES) trains in urban rail transit is gradually increasing, leading to distinct energy-saving driving strategies compared with conventional grid-powered trains due to the unique characteristics of OBES. The optimal control conditions (OCCs) and energy-saving speed profile optimization methods of OBES trains are studied. Considering the unique power coupling constraints of OBES trains, an optimal control model with OBES as the control variable for minimizing energy consumption is established. Subsequently, based on Pontryagin’s maximum principle, the OCC of the OBES trains is derived, in which the balanced power (BP) condition is determined as the energy-saving condition. The BP insertion algorithm is designed to generate punctual energy-saving speed profiles. Simulations on a tram powered by supercapacitors (SCs) show that the proposed algorithm can obtain an energy-saving speed profile that satisfies the constraints. Compared with the cruise strategy as a benchmark, the proposed OR_BP has an energy-saving rate of 9.23% in the actual track. On different tracks, OR_BP has high computing efficiency while ensuring the energy-saving effect. Finally, the effects of different parameters and models of the SC are analyzed.