Reducing fuel consumption and related emissions through optimal sizing of energy storage systems for diesel-electric trains

Analysis of Hybrid and Plug-In Hybrid Alternative Propulsion Systems for Regional Diesel-Electric Multiple Unit Trains

“…The simulation model was developed in the MATLAB ® /Simulink © environment using the OPEUS Simulink toolbox [59]. The model of a hybrid DEMU [37] was extended to include different power sources (i.e., ICE, pantograph, LB, and DLC) and to capture the dynamics of ESSs using typically available parameters published by the manufacturers. The simulation model (Figure 2) allowed for the simulation of different configurations by disconnecting components not included in the respective system.…”

“…The vehicle resistance R v [N] includes roll resistance and air resistance, modelled using the Davis equation [60], with vehicle-specific coefficients r 0 [N], r 1 [N/(m/s)], and r 2 [N/(m/s) 2 ]; R g [N] is the grade resistance, with g = 9.81 m/s 2 denoting the gravitational acceleration, and γ [rad] the angle of the slope [61]; and the curve resistance R c [N] is calculated using Roeckl's formula [62], with φ [m] denoting the curve radius. With the given wheel diameter, d w [m], and the vehicle velocity, v, the torque at the wheel, T w [Nm], and its rotational speed, ω w [rad/s], can be calculated by [37,43].…”

“…The power from the EM shaft to the wheels is transmitted via the axle gear, with the constant gear ratio i ag and the constant efficiency of the gearbox η ag . The torque T EM [Nm] and the rotational speed ω EM [rad/s] at the mechanical input of the axle gear result from [37,43].…”

“…Based on the operation mode (motor or generator), and with the EM efficiency η EM = f EM (T EM , ω EM ) determined by a linear 2D-interpolation in the efficiency map, the electric power of the electric motor P EM [W] can be determined by [37,43].…”

“…Their aim is to minimize energy consumption by managing the power flows from different energy sources in the system. Dynamic programming (DP), as a global optimization method, is widely used in EMS optimization for hybrid railway vehicles [37][38][39]. It was also used in deriving a fuel-optimal combined driving and energy management strategy [40].…”