Study and simulation of the energy balance of an urban transportation network

This paper proposes and studies new strategies for an increase of the energetic efficiency of an urban transportation network fed with catenaries. A simulation tool has been developed to determine the energy efficiency on the global transportation system (vehicles, feeding line and substations). The system energy consumption is identified by calculating the energy injected by the substations to the feeding line. It takes into account all the line losses and the interactions between the different vehicles on the line. The development of a new tool was necessary as other simulation tools calculate the energy consumption of the tram without taking in account the line properties and the interactions between the vehicles. Using this simulation tool, the energetic efficiency of a tram is studied while on board of the vehicle a supercapacitive energy storage has been added. The energy storage allows local energy recovery and injection of energy to the catenaries during braking phases. The results of simulations with or without on-board energy storage and with overhead lines with high resistive or standard behavior are presented. The results show that the global energy efficiency of the system (trams, feeding line and substations) is increased by a factor between 19.4 and 25.6% (depending on the vehicle auxiliaries power) by adding a supercapacitive energy storage for both cases presented in this paper: high and standard line resistance. The use of a high line resistance instead of a standard line resistance increases the efficiency of the total system by an additional 5%.