Railway safety cases on traction drives using train simulation
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Railway Technology Consulting

Technology Consulting for Traction Solutions

Alstom's Pendolino Train - WCML Class 390

Virgin's Tilting Pendolino on WCML - London to Glasgow at over 125mph

This site is dedicated to technical discussion and issues related to electric / electronic traction drives and railways. Taking the train above as an example, critical railway standards required expert EMC compliance demonstration before the Alstom manufactured Pendolino trains could enter UK passenger service. Some of the analytic and simulation safety methodologies are described, including Cecube Components, a unique software set for traction drive and train simulations.

Now available - the concluding topical article about Energy Efficient application of Regenerative Braking on railway networks.

To establish the susceptibility of existing track signalling relays to traction current on electrified railways the relays are modelled in detail. The electromechanical models are verified against carefully controlled bench testing of the relay. The relay model is then inserted into a track circuit model that reflects its length, type of track, installed cross-bonds & track circuit feed arrangements. The track circuit model then introduces interference from a train source, sited at any location to compute its vulnerability. A track circuit deemed at risk from credible traction sourced emissions is then subject to immunisation upgrades until a satisfactory safety margin is established. The Matangi fleet has benefited from this type railway infrastructure enhancement.

Relay Model

Schematic of the Mechanical Behaviour of a 50Hz Track Relay

TOP-FACE is a generic EMC network modelling system for Topographical Interfaces (graph below), using inputs from track layout, lineside system geometry, the position of track circuits and trains, plus geographical inputs from sources like Google Earth & Maps. Unlike previous approaches very few assumptions are made, since the interface model is an amalgamation of many individual sections, each individually programmable. A unique railway network section can be simulated and electrical coupling from one part of the network to another analysed. Trunk routes frequently involve more than one network, with potential for electrical interaction between neighbouring railways. The simulation can comprise many kilometres of track, or specifically target railway stations, junctions and tunnels. It has been validated against results in BR13422.

TOP-FACE EMC coupling

Interaction with Neighbouring Railways & compatibility with NR/GN/SIG/50018

We provide railway applications support to these general purpose, engineering products for each of the following railway sectors:

  • Frequency domain modelling of track sections to establish emissions coupling with own and neighbouring railways
  • Time domain power electronic models to analyse vehicle propulsion and traction supply systems
  • Reliability modelling to determine credible failure modes and the risk to signalling safety and railway operational integrity
  • Control system modelling in time or frequency domain to determine system stability of train or supply system.
  • Train performance models for evaluation of component ratings, thermal effects and motor performance

The SITE MAP provides more links to newsletters and other articles, including a series on the theory of traction energy saving by electrical regenerative braking. This theory underpins minimising environmental damage in the railway transport sector with sustainable solutions. In the first of a series of articles on how to maximise electric regeneration on railway systems, the impact on service run time is considered. Further articles analytically establish generic relationships between the total energy consumed with rail network topology and rolling stock design, explaining sensitivity to critical parameters. This promotes a design balance that optimizes energy efficiency without compromising the size, cost, and unsprung mass of the traction equipment.

The buttons above navigate to the case study examples, video clips and free downloads. If you wish to initiate your own simulation exercise, one of the readily available proprietary SPICE or MATLAB environments is highly recommended. Please see the software and simulation pages for advice on selection and functionality. Discover twenty years of Cecube publications on PWM harmonic elimination, AC motor traction drive control, EMC interference, Train simulation, and Power electronics. For an in depth explanation click the following link or the papers on railway technology button in the top left column. You can view a heavy duty locomotive in creep control via the computer simulation link and then learn how it was modelled in a descriptive and illustrated simulation tutorial. If waveform generation is a mystery then understand more by clicking on PWM and studying the video clips. There are also bespoke model downloads for evaluation on the railway software page. Railway technology safety issues are discussed in the Railway Safety Case page. This considers the safety impact of modern traction drives on railway infrastructure.

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