Heavy haul locomotive traction performance under the implications of in-train forces

This paper conducted co-simulations to examine locomotive traction performance in a heavy haul train operational environment. A Longitudinal Train Dynamics (LTD) simulation package was connected with a multibody vehicle system dynamics simulation package called GENSYS using the TCP/IP protocol. The LTD simulations replicated the dynamic environment (in-train forces) of train operations while the vehicle system dynamics simulations integrated wheel/rail contact models and mechatronic traction control models for locomotives. In-train forces and a traction reference were sent to GENSYS to determine traction efforts which were then sent back to LTD. A distributed-power train with the configuration of 1 locomotive + 61 wagons + 1 locomotive + 61 wagons was modelled. A conventional LTD simulation and a co-simulation were conducted. The results show that, due to adhesion limits, both LTD and co-simulation did not achieve the maximum traction force specified by locomotive characteristics curves. The maximum traction force achieved in co-simulation was 170 kN lower than that in LTD simulation. The average speed simulated by co-simulation was about 10% slower than that by LTD.