Research Brief Simulation and verification of results from 125mph current collection modelling for two pantographs Overview On behalf of the Vehicle / Train Energy System Interface Committee (V/TE SIC), RSSB carried out an investigation supporting operation of multiple unit high speed trains on the East Coast Main Line (ECML). The deliverables from this research project are specifically aimed at those with a technical understanding of the current collection interface. Currently, ECML trains are hauled by a single pantograph, Class 91 locomotive, travelling at speeds of up to 125 mph. Future plans include the operation, at similar speeds, of two-pantograph multiple unit formations. This will adversely influence the achievable standard of current collection. The results of the research were used to: o Inform the understanding of overall performance and operational risk associated with the use of two pantographs, at running speeds up to 125mph (with varying distances between the pantographs, dependent upon train configuration). o Investigate a range of potential improvements to pantographs or overhead contact line to enhance current collection performance at pre-defined Intercity Express Project (IEP) pantograph spacings (dpto). The research established that the necessary level of performance cannot be achieved for multiple pantographs at 125 mph with the existing pantograph and overhead line equipment. Although the research identified a potential performance gain when using a lighter alternative pantograph and increased overhead line (OLE) tension, these system improvements alone were insufficient to improve performance to achieve 125 mph operation. Other issues beyond current collection, such as resulting gauge clearance, compatibility with GB section insulators, neutral section design and structural capacity of the OLE equipment were not addressed. RSSB R&D Programme Block 2 Angel Square 1 Torrens Street London EC1V 1NY research@rssb.co.uk www.rssb.co.uk/research/pages/ default.aspx 1
Simulation and verification of results from 125mph current collection modelling for two pantographs Aims The aim of this research project was to investigate the use of multiple-pantographs on the current ECML OLE, to ascertain the level of current collection performance with IEP pantograph spacings. It investigated: Whether speeds of 125mph could be achieved with a multiple pantograph collection system. If not, what level of performance could be achieved. What system changes would be needed to achieve compliant current collection at a consistent speed of 125mph. Method The research project used the SNCF OSCAR dynamic simulation tool, which was developed from the UIC sponsored EUROPAC project and is a programme used for similar EU studies. The project was undertaken in three stages: 1 Define and set up the model and verify it against physical measurements taken from Class 91 testing on ECML. This established two virtual test zones, on the ECML, between Grantham and Newark-on-Trent. 2 Use the verified OSCAR model to predict the current collection performance of the proposed Intercity Express Programme (IEP) train configurations using the existing Class 91 pantograph on the ECML virtual test zones. 3 Undertake sensitivity analysis to establish potential modifications to the pantograph and OLE that could improve current collection. The Class 91 testing was carried out in March 2009. The test trains consisted of two Class 91 locomotives with five and nine Mark 4 coaches, to give two operating pantographs at distances of 126 m and 220 m. [The usual Class 91 formation includes a driving van trailer, with no pantograph.] The two test zones selected for the simulations consisted of one two-track section with a nominally level contact wire; and another section with a number of specific features, such as a bridge, graded contact wire, and headspan supports. This represented plain line and one with more complex features for which equivalent test data was available against which to correlate results. Following evaluation of the limits with the proposed IEP train configurations, sensitivity analysis was carried out that looked at varying the mass of the pantograph head and reducing the 2 RSSB
contact force on the front pantograph. In addition, potential modifications to the OLE were considered, which included increasing the contact and catenary tension from 11 kn to 12 kn and 13 kn. The modelling simulations only assessed the current collection aspects. The impact on clearance, and compatibility with existing overhead line were not considered, these being beyond the scope of the dynamic simulation study. Finally, simulations were carried out using an alternative 'monoband' pantograph with a single contact strip; this has been used with success and benefit to collection dynamics in France and represents the lowest weight pantograph commercially available. Deliverables The research has delivered the Simulation and verification of results from 125mph current collection modelling for two pantographs - technical report. This report presents the data inputs, the verification and validation processes, inputs to the OSCAR model, simulation results, and the conclusions drawn. This report is available to RSSB members, on request and will not be published. Findings The current collection limits applied to the results correspond to the existing level of performance with the Class 91 pantograph on ECML. The technical report also considers the minimum TSI limits which would, by comparison, give a reduced level of performance. The work has established a verified model of the ECML overhead line equipment. It also established, from the test results, that the necessary level of performance cannot be achieved for multiple pantographs at 125 mph with the existing pantograph and overhead line equipment. The speed limits for the nominal spacings for the IEP trains with existing pantographs were established as follows (where current collection criteria used is mean contact force - 3 x standard deviation, is greater than or equal to 25N ie Fm-3 >25N): RSSB 3
Simulation and verification of results from 125mph current collection modelling for two pantographs Table 1 - Achievable speeds for the IEP train using three distances between pantographs (d pto ) Limit speeds for IEP train Open route Bridge + level crossing + headspans 179.8 km/h 158.2 km/h 161.2 km/h 161.0 km/h 180.8 km/h 154.4 km/h By optimising the pantograph parameters (M = pantograph head mass, alpha = percentage of permissible upward force), the following improved limits can be achieved: Table 2 - Simulated limit speeds for the IEP train using nominal and optimised pantograph parameters Simulated limit speeds for IEP train Nominal parameters M=7.8kg, alpha=1 Optimal parameters (M=5kg, alpha=0.9) 170.7 km/h 181 km/h 163.6 km/h 170.6 km/h 175.8 km/h 180.3 km/h The performance improvement to be gained by modifying the pantograph parameters alone is relatively small and is considered insufficient to achieve reliable performance at 200km/h (125 mph). By increasing the tension in the contact and catenary, the following results were obtained: 4 RSSB
Table 3 - Simulated limit speeds achievable using different catenary tensions Simulated limit speeds for IEP train Nominal parameters (T=11kN) T=12kN T=13kN 170.7 km/h 177.7 km/h 190.1 km/h 163.6 km/h 175.6 km/h 178.8 km/h 175.8 km/h 178.5 km/h 173 km/h A large improvement is obtained by increasing the OLE conductor tension from 11 kn to 12 kn (increase of the limit speed by 12 km/ h), whereas the improvement is much lower from 12 kn to 13 kn (and even negative for the 207 m configuration). Nevertheless this alone will also not improve performance sufficiently to achieve 200 km/h (125 mph) operation. By combining the pantograph and OLE parameter modifications and adopting a small reduction in the pantograph head mass, that is simpler to deliver without significant changes to the head design, the following results were obtained: Table 4 - Simulated limit speeds for the IEP train using combined nominal and optimal parameters Simulated limit speeds for IEP train Nominal parameters M=7.8kg, alpha=1, T=11 kn Optimal parameters M=7kg, alpha=0.9, T=12 kn 170.7 km/h 182.9 km/h 163.6 km/h 178 km/h 175.8 km/h 183.1 km/h In this case the combined modifications increase the limit speed by 14.4 km/h, from 163.6 km/h to 178 km/h. RSSB 5
Simulation and verification of results from 125mph current collection modelling for two pantographs Finally, taking a typical monoband pantograph, the following results were obtained with a tension of 11 kn and 12 kn. Table 5 - Monoband pantograph head speed limits for IEP train, obtained with T=11 kn and 12 kn, using Fm-3 >25N criterion Limit speeds for monoband T=11 kn (existing) T=12 kn 182.4 km/h 192.1 km/h 171.9 km/h 173.2 km/h 179.5 km/h 188.3 km/h The report indicates that when alternative acceptance criteria are applied, a higher operating speed can be achieved. When the TSI criterion of /Fm <0.3 is used, in conjunction with 12 kn wire tension, each pantograph configuration can exceed 205 km/h using the monoband pantograph. Network Rail, however, currently applies Fm-3 >25 N in assessment of the existing ECML operation; and this criterion has been retained, so that equivalent service reliability is returned. This results in a reduction in the achievable operating speed as shown in table 5. Next steps This research has provided the Department for Transport (DfT) and V/TE SIC with valuable information about the limitations of the existing overhead line systems when interfaced with a train of IEP specified multiple pantograph spacings and speed, prior to their procurement. The V/TE SIC has also accepted the conclusion that the use of a pantograph head with low unsprung weight and employing conductors of higher tension would improve the current collection profile. The research highlights the potential of alternative acceptance criteria so for any future aspiration for operation of multiple pantographs at 125mph or higher it may be appropriate to review these in any evaluation of compatibility and as part of the economics of modifications to the OLE tension and other updates to the OLE. In the meantime, the potential benefits associated with further reductions in pantograph weight are considered by 6 RSSB
the V/TE SIC to be the most simple to achieve but would require a dedicated next generation pantograph design development programme if the current collection is to be delivered at the prescribed interface. The Future Electrification Group (FEG), a sub-group of the V/TE SIC, reviewed the findings. The FEG has agreed that Network Rail (the infrastructure manager) was best placed to lead any future review of the acceptance criteria for current collection for both Intercity and EMU operation should the need arise. The DfT has accepted the FEG recommendation to review the pantograph strategy for GB rail and to decide whether the development of the next generation pantograph should be supported by UK Government funding. Contact For more information please contact: Head of Engineering Research R&D Programme RSSB research@rssb.co.uk RSSB 7