OPEUS D5.2 - Analysis of energy losses in the traction chain
Creators: name: Partner-STAV
Publisher: name: Zenodo
Year: 2020

description: The work presented in this Deliverable D5.2 has been carried out in the framework of the EU Project OPEUS. This deliverable presents the analysis of energy losses in the reference rail vehicle architectures described in previous OPEUS task 5.1 and an investigation on different vehicle parameters and strategies to improve energy consumption. The first part of this report shows the energy loss distribution diagrams for all rail service categories or scenarios in order to identify the energy losses in the traction chain as well as the components having a higher influence in energy consumption. Component efficiencies are analysed for the operation modes. For rail vehicles with AC supply (which follow Topology T01) it is concluded that the traction motor and transformer are the biggest contributors to energy losses, they together represent up to 71.46% of overall energy losses in the case of suburban, with a minimum of 66.34% in the case of intercity scenario. For rail vehicles with DC supply (which follow Topology T03) it is concluded that the traction motor is the biggest contributor to energy losses, accounting for 67.74% and 66.61% in the case of the tram and metro scenarios respectively. Energy loss distribution is also analysed for a Tram with ESS, where the traction motor accounts for the majority of the energy losses too, with 45.67%. However, in this case, the introduction of the ESS and its converter represents the second highest contributor to the energy losses, contributing to 33.8% of the overall energy losses. Despite the additional weight of the ESS components, the consumed traction energy at the catenary is nearly the same regarding the one of the reference scenario. But in addition, the ESS scenario allows for halving the power peaks at the catenary which is beneficial for the net characteristics. An analyses on the operational phases is made for the different rail scenarios to quantify the energy losses during acceleration, cruising, coasting and braking. Depending on the service and route characteristics the losses are concentrated in different phases, e.g.: in urban services the major energy losses are concentrated in the acceleration phase and also in no traction phases (coasting and stops at stations), while main line services like freight or high speed have considerably energy losses during cruising operational phase. The last part of the report makes a sensitivity analysis to investigate the impact in the energy consumption of different vehicle parameters and strategies: The effect of auxiliary loads occurring during the different operational phases are investigated in the tram scenario. Traction motor switch-off strategy is implemented in all scenarios, finding out that urban and regional services have the biggest energy savings, achieving 9% energy savings in the case of the tram scenario. The influence of the tare mass parameter (+/- 10 %) is analysed in all scenarios, having considerable energy improvements for lighter trains: up to 8.25% energy savings in the case of the metro. The effect of the aerodynamic drag of the train vehicle is investigated through the resistance factor, resulting that a 10% reduction in factor causes a 5.66% reduction in HS300 energy consumption. Finally, the influence of the rotating masses is also investigated, finding out hardly influence on energy consumption. The analysis concludes that in both AC and DC rail vehicles, the traction motor is the highest contributor to energy losses, especially during no load operation. Therefore, the implementation of partial switch-offs of traction components has the most significant effect on energy savings, if it is utilised on a service with long coasting phases or standstill at stations. Due to the high portion of standstill and coasting, urban and regional services offer the most significant potential for the application of this operating strategy. However, if a service has hardly coasting times and a high time percentage of traction phases other strategies may apply. In the last case a train mass reduction can be very interesting, as acceleration power is directly related to the hauled mass. In addition, the improvement of aerodynamics will significantly improve the energy efficiency in high speed services. Finally, it is expected that new E-transformers, with higher energy efficiency than conventional transformers, contributes to reduce overall energy losses in rail vehicles with AC supply. This is checked in OPEUS Deliverable 3.4, which provides an overview of some innovations of the Shift2Rail technical demonstrators, including the improved energy efficiency of the transformers.