energy consumption assessment in a dc electric railway system with regenerative braking: a case study of isfahan metro line 1

Regeneration of electric energy during braking is an important issue in electric railway systems. especially in older electric railway systems that have non-reversible dc traction substations, the goal is to modify the structure of the dc traction substations and replace them with reversible converters at the lowest cost. accurate evaluation of the power flow and the energy distribution in an electric railway system needs a comprehensive study of the whole railway system with multiple moving trains. but, the modeling and simulation of an electric railway network are complicated due to its nonlinear, time-variant, and large-scale structure. this paper presents the electric energy distribution in the isfahan metro line 1 with and without regenerative braking. for this purpose, a simulator is developed for the dc electric railway systems with multiple moving trains. driving control strategies, including coasting control, have been applied. the understudy system consists of 7 dc traction substations and 10 trains traveling on the up track. different scenarios have been simulated with various combinations of reversible and non-reversible dc traction substations. results reveal that the electric energy consumption of the system with regenerating trains and reversible dc traction substations is 27.13% lower than the system without regenerative braking. to mitigate the energy consumption in the isfahan metro line 1 using the regenerative braking system, it is not mandatory to upgrade the structure of all 7 dc traction substations. results show that it is possible to reduce electric energy consumption by 26% through installing only 5 reversible traction substations.