Optimal capacity and positioning of stationary supercapacitors for light rail vehicle systems

This paper presents a criterion for the design of the optimal capacities and locations of stationary supercapacitors for light rail vehicles. The design criterion is based on a single train simulator, which uses an electrical and mechanical model of a light rail vehicle travelling across an electrified track with stationary supercapacitors. The train power and current are obtained by the characteristics of the traction system. The optimisation problem takes into account the isoperimetric constraint that the average power supplied by supercapacitors during every cycle is nil. The optimisation process minimises the difference between the train voltage and the nominal line voltage, the electrical energy consumption of the train and the storage capacity. The suggested procedure gives information on how the storage capacity is affected by the position of supercapacitors along the track. The results obtained show that the minimal capacitances are obtained when supercapacitors are close to the substations for each section of the electrified line. Finally, the paper presents a simple comparison between practical designs of supercapacitors for each section of the line using commercially available modules.