It is also interesting the analysis of the behavior of these
systems in emergency operation, in order to find solutions to
protect the electrical system components and the system as a
whole. Recent studies focus on short-circuit current
determinations using analytical methods or simulations. Even if
some dc transportation systems were analysis [9], most of these
researches refer to ac traction systems [10]–[12]. They have in
view mainly to analyze the transformer behavior [12] and to
propose a better protection system for the equipment and
personnel [9], [11], [13].