Optimal Energy Management and Sizing of a Battery-Supercapacitor-Based Light Rail Vehicle with a Multiobjective Approach

In this paper, an optimal energy management strategy (EMS) for a light rail vehicle with an onboard energy storage system (ESS) combining batteries (BT) and supercapacitors (SC) is presented. The optimal operating targets for the proposed EMS and ESS sizing (BT+SC) are obtained by multiobjective (MO) optimization with genetic algorithms. The MO fitness function is expressed in economic terms and includes the cost of the energy absorbed from the catenary, as well as the operating cost of the BT and SC pack (initial investment and cycling cost). The case study selected is the tramway of Seville. The aim is to minimize the daily operating cost of the tramway, taking into account the fulfillment of the tramway performance in the catenary-less zone and the BT-SC degradation by cycling during operation. Furthermore, a sizing analysis is done by comparing the current scenario (SC-based) with the proposed approach (optimal EMS and sizing) in terms of daily operating cost reduction.