Advanced Engineering for Railway Rolling Stock
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Advanced engineering for railway rolling stock Moving to a new engineering dimension criticalsoftware.com [email protected] White Paper Advanced Engineering for Railway Rolling Stock The liberalisation of rail transportation in Europe, which started in the 1990s, TRACTION CHAIN has changed the railway market. The flow of goods is moving quickly over ever What causes the train to accelerate and brake greater distances, while the logistics are becoming more complex. Consequently, are the adhesion forces that appear in the the manufacturers of rolling stock, namely locomotives, have to meet an wheel-rail contact. For these adhesion forces increasing number of demands due to altered statutory requirements, as well to effect, tractive or braking effort needs to as new standards and directives. be applied to the wheels. This torque must be generated in a motor or braking system that MARKET DEMANDS, AS WELL AS CUSTOMER FEEDBACK, MUST ALSO transforms a certain amount of energy into BE CHANNELLED INTO THE PRODUCT LIFE CYCLE. the required mechanical energy. As most freight traffic in Europe is cross-border, in order to provide a competitive advantage, locomotive manufacturers must overcome a major challenge: interoperable services. In order to operate cross-border, manufacturers must support different catenary voltages (15kV AC, 25kV AC, 3kV DC and 1.5kV DC), different types of pantographs, different train radio systems, different loading gauges, to name just a few of the many national Figure 2: Results of bad traction control requirements. The locomotive traction chain combines various equipment, allowing the locomotive to move. Railway traction is essentially supported by two different propulsion systems: electric or diesel. Electrical traction units can be of the following types: • DC traction units, which use direct current drawn from either a conductor rail or an overhead line AC traction units, which draw alternating current from an overhead line • Multiple-system units, which can operate under several different voltages and current types: the locomotives do not have to stop when passing from one electrification system to another as the changeover occurs where Figure 1: Trans-European Transport Network the train coasts for a short time In a diesel locomotive, the diesel engine drives IN ADDITION, ONE OF THE MOST DIFFICULT CHALLENGES TO an electrical DC generator or an electrical AC INTEROPERABILITY ARE THE AUTOMATIC TRAIN PROTECTION (ATP) alternator-rectifier, the output of which SYSTEMS; THESE SAFETY SYSTEMS HAVE A HIGH SAFETY INTEGRITY provides power to the electric traction motors. LEVEL AND ARE RESPONSIBLE FOR THE PROTECTION OF PERSONS An electro-diesel locomotive can operate as an AND GOODS. electric locomotive on electrified lines, with an on-board diesel engine for non-electrified ROLLING STOCK EQUIPMENT AND SYSTEMS sections. With this capability, the same locomotive is able to leave the freight in the LOCOMOTIVE PRODUCT CONCEPTS correct location without the need for another The product concept provided by some of the biggest manufacturers (Siemens' locomotive. Vectron; Alstom's Prima; Bombardier's TRAXX) covers single and multi-system locomotives for the European alternating-current (AC) and direct-current (DC) 3 1 7 4 6 networks for high-speed passenger traffic and interoperable cross-border 2 9 TCMS freight traffic. To enable the capability of operating on non-electrified lines, the 5 8 manufacturers also provide diesel-electric versions of these same locomotive platforms. Figure 3: Locomotive traction chain One interesting aspect is that the platforms of all these major locomotive The locomotive traction chain is composed of manufacturers have, in reality, a very similar architecture. They rely on similar the following main components, which may main subsystems and functions to provide the customer a very flexible usage. vary depending on the type of locomotive: 1) TRACTION TRANSFORMER 4) TRAIN CONTROL & 7) AUXILIARY CONVERTER 2) TRACTION CONVERTER MONITORING SYSTEM 8) BATTERY CHARGER 3) TRAIN CONTROL 5) TRACTION MOTOR 9) ENERGY STORAGE © Critical Software. All rights reserved. 6) DIESEL ENGINE GENERATOR White paper BODY STRUCTURE The locomotive body structure is typically designed as a self-supporting structure that meets high mechanical strength requirements. It should be capable of withstanding stresses from load cases according to applicable standards, i.e. it should withstand the maximum static tensile and compressive forces. The design of the two driver cabs should ensure survival space in crash scenarios, according to applicable standards. MACHINE COMPARTMENT The machine compartment layout is determined based on factors including customer requirements, economical use of space, ease of maintenance, clarity, safety, flexibility and convertibility. BOGIE MODULE The bogie comes in many shapes and sizes but it is, in its most developed form, the motor bogie of an electric or diesel locomotive. Bogies are classified into various types according to their configuration; in terms of number of axles, the design and suspension structure. Bogies are subjected to severe stresses and shocks and may have to run at high speeds. Railcar bogies usually go unnoticed by rail passengers, but despite their obscurity, they are one of the most vital components of rolling stock: • They support the railcar body firmly • They run stably on both straight and curved track • Ensure good ride comfort by absorbing vibration (generated by track irregularities) and minimising impact of centrifugal forces (when the train runs on curves at high speeds) Many safety concerns should be considered with bogies, since a damaged bogie may put lives at risk. MONITORING SYSTEMS ARE BEING SPECIALLY DESIGNED TO MONITOR THE PHYSICAL PROPERTIES OF BOGIES, WHEELS AND SUSPENSION, E.G. TEMPERATURE, VIBRATIONS AND SHOCK ABSORBER CAPABILITIES. WHENEVER ONE OF THESE PARAMETERS EXCEEDS A PREDEFINED LIMIT, A MAINTENANCE WARNING IS ISSUED AND REPAIRS ADVISED. TRAIN PROTECTION EQUIPMENT The train protection equipment is installed on specific cabinets in the machine compartment of the locomotive. The train protection cabinets are typically designed with a modular structure, so that conversion or retrofitting can be easily performed. Train protection systems are of vital importance in maintaining the safety of the complete rolling stock structure. Their main function is to monitor the different systems involved and the surroundings – especially the trackside equipment data – to maintain train safety according to defined rules. Automatic train protection systems are generally found inside a locomotive with a higher safety integrity level. Whenever a safety rule violation is detected by the automatic train protection system, the ATP will put the rolling stock in a safe state. Generally, this safe state means the system stops the train before an accident could happen, making people and goods safe. The underfloor area and the bogie are pre-prepared for the mounting of antennas and speed encoders; the sensors used to monitor the trackside data. White Paper Advanced Engineering for Railway Rolling Stock SOFTWARE SERVING YOUR BUSINESS – IT’S MORE THAN JUST A change in infrastructure costs CODE millions, far more expensive than the cost of changing only some rolling TRAIN MANAGEMENT SYSTEM stock items. This option is more The system that performs train control and continuous monitoring of train attractive, not only for the companies status, the 'brain of the train', integrates all control and communication operating freight or passenger functions on board. It provides train, vehicle and drive control functions including services, but also for governments operating and comfort functions, as well as train diagnostics. discussing modernisation projects or construction of new infrastructure. Train Management Systems (TMS) can integrate multiple subsystems developed at various Safety Integrity Levels (SIL). The main components of Software will play an interesting role these systems are: the Vehicle Control Unit (VCU), which is a general processing in this particular market; using unit that provides vehicle management and control functions; the Drive Control configurable software applications in Unit (DCU), that controls and supervises the functions of the traction converter; these safety-critical systems will and I/O modules, to provide an interface to additional systems, typically leverage manufacturers to better through low voltage signal lines. Due to safety concerns, subsystems such as respond to the needs of their VCU and DCU in particular should be developed accordingly with a high SIL, in customers. accordance with CENELEC standards EN 50126, EN 50128 and EN 50129. The backbone of modern TMS is based in a Data Communication Bus for intra-vehicle communication, and for train-wide information exchange. The TMS streamlines the flow of information between trains and wayside equipment. It collects and provides real-time information allowing proactive transit security and vehicle maintenance. VCU Data communication BUS DCU I/O Modules High voltage power line 24V signal lines Traction Brake Lever Converter Figure 4: Typical rail vehicle control architecture Current tendency is to increase the use of networks for the signal transmission, using remote transmission units that interface with the sensors and pack the necessary information into a network. This method of design has the advantage of reducing the total cable length necessary in the locomotive, while increasing