Energy regeneration in transportation systems. Methodologies for power-networks simulation.

The problem of the simulation of d.c. electrified ground transportation networks is discussed in this paper, with specific regard to the methodologies for computing power-network. An analysis of the influence of different numerical methods on computing time is presented with specific regard to the traffic simulation in a model rapid-transit system, in wich trains equipped for regenerative brake and electric substations with or without inverters were assumed to operate. The importance of the choice of initial voltage conditions and of the tolerance degree is also discussed. Some aspects of the simulation have been validated by comparing the results of tests carried out by an experimental plant, which consists of a single reversible electric substation and two trolleybus reversible drives. The article shows that some numerical methods widely used for transmission networks computation can be, with simple adjustments, advantageously used to calculated the networks for electric traction, balancing the need to limit the computer time with that of obtaining an accurate simulation, of general application. Moreover, the vehicular loads can, thus, be defined directly, starting from the power demanded (or regenerated).