Modeling, Simulationand Analysis of On-Board Hybrid Energy Storage Systems for Railway Applications

Abstract

In this paper, a decoupled model of a train including an on-board hybrid accumulation system is presented to be used in DC traction networks. The train and the accumulation system behavior are modeled separately, and the results are then combined in order to study the effect of the whole system on the traction electrical network. The model is designed specifically to be used with power flow solvers for planning purposes. The validation has been carried out comparing the results with other methods previously developed and also with experimental measurements. A detailed description of the power flow solver is beyond the scope of this work, but it must be remarked that the model must by used with a solver able to cope with the non-linear and non-smooth characteristics of the model. In this specific case, a modified current injection-based power flow solver has been used. The solver is able to incorporate also non-reversible substations, which are the most common devices used currently for feeding DC systems. The effect of the on-board accumulation systems on the network efficiency will be analyzed using different real scenarios.

Non‐linear switched model for accurate voltage estimation and power flow analysis of DC railway systems

“…It is activated by the ‘over‐voltage protection’ (Fig. 3 b ) [15, 18]. This does not cause any delay, but this reduces the overall efficiency.…”

“…In such a case, on‐board ESS can offer off‐grid traction possibilities. More details about such technologies and other examples are in [5–16].…”

“…[3, 4] and improving the infrastructure. Different solutions are, therefore, envisaged such as reversible traction power substations (TPSs) [5–8], energy storage systems (ESSs) [2, 8–16], or renewable energies [16]. Optimisation techniques are also often used to improve the operation of specific subsystems (i.e.…”

“…Indeed, they represent non‐linear behaviours, which require complex models that are generally solved using numerical iterative techniques [19, 20]. Most existing and commercial tools consider the train as a static current source and use the conductance matrix iterative approach known as the current injection (CI) method [12–15, 18–20]. These currents are then injected into a modified nodal analysis (MNA) method to solve and analyse the DCTN in a specific configuration according to the injected currents [21, 22].…”

“…However, most simulation tools simplify this second phenomenon and only consider the increase in voltage due to the resistive part of the DCTN [19]. This problem is generally solved by considering reversible TPS or ESS [5–16], which contribute to improving receptivity. Other works aiming at estimating the energy consumption neglect this phenomenon because it occurs when all the TPSs are blocked, which do not lead to a significant error on global energy consumption [24].…”