Light Rail/Rapid Transit: New Approaches for the Evaluation of Energy Savings, Part II - On the Receptivity of a Transit System

New approaches are presented for the determination and evaluation of regeneration in large transit systems. A specific definition of the receptivity of transit systems to available regenerative braking energy is presented, and the analytical base for receptivity evaluations is developed. The construction of a transit system operational model also is described. This operational model is the mechanism by which the values required for the receptivity analysis are generated. The resulting analytical method provides efficient computation by identifying characteristics peculiar to transit system operation and making use of random sample rather than real time techniques. The analysis also uses a simplified network for the transit system (referred to as a single-thread model) that is error-biased to give a worst-case calculation of receptivity so that a lower-than-actual limit always is predicted. The operational model can be used with the synthetic routes described in the companion paper [21] to determine energy consumption values and, thus, life-cycle cost benefits. Through the use of these analytical tools and simulations, a complete evaluation of potential energy savings can be performed at a reasonable computing cost. A complete receptivity analysis, including parameter sensitivity scans for the Toronto Transit Commission´s large streetcar fleet, is presented. The analysis predicted that the weighted average receptivity of the streetcar fleet will be in excess of 97 percent with a voltage window of 110 V or more, and that this result is essentially insensitive to the per-car auxiliary power and to moderate variations in the power distribution system resistances.