Pantograph-Catenary: a European couple

L.-M. Cléon1, A. Bobillot1, A. Collina2, O. Mohamed3 (track-side monitoring station), V. Loverre4 1SNCF Research Department, Paris, France; 2Politecnico di Milano, Milano, Italy; 3DB Systemtechnik,

München, Germany; 4Mer Mec, Monopoli, Italy

Abstract

The Europac (EURopean Optimised PAntograph Catenary interface) project is gathering major European railway stakeholders1 around a research project on vehicle-infrastructure interaction through the pantograph-catenary contact. The project aims at enhancing interoperability between pantographs and catenaries all over Europe, decreasing the number of incidents related to this system, and reducing maintenance costs by switching from preventive maintenance to corrective maintenance. On that purpose, Europac is developing a comprehensive system composed of a joint software for interoperability, a track-side monitoring station and an on-board monitoring system.

Introduction

Two vehicle / infrastructure mechanical interfaces are present in the railways. The first consists in the wheel / rail contact, which has been a topic of research for many years, concerning safety and comfort, from the modelling and experimental point of views. The second consists in the pantograph / catenary contact, in which much less research has been performed. However, this interface is of crucial importance, since it implies interoperability issues, contrary to the wheel / rail contact. Moreover, it constitutes a limitation for increasing the train speed due to the wave propagations in the very flexible catenary. Finally, defects in the catenary often lead to the rupture of the contact wire and consequently to the stopping of the train. Consolidated statistics from DB, SNCF and Trenitalia show an average number of 915 incidents per year leading to 443 000 minutes of delay, generating tremendous costs to the railway stakeholders in particular and to the society in general. The Europac project, funded by the European Commission, is dedicated to this problematic through three main topics: simulation, track-side and on-board monitoring. Concerning the simulation of the pantograph-catenary dynamic interaction, Europac will develop a software designed to predict interoperability between any present or future pantograph and catenary. Moreover, this software is intended to take into account up to now unaddressed effects of deteriorated conditions such as extreme temperatures, cross-winds, wear or defects in devices. A shown in figure 1, it is based on a fully three-dimensional Finite Element modelling of the catenary and on a Multibody modelling of the pantograph. Moreover, it will allow specific studies of singular points and perturbed situations. The signatures obtained from these simulations will be used to develop the intelligence of the measurement expert systems.

1 Société nationale des chemins de fer français, Alstom, Arttic, Banverket, Ⴠeské dráhy akciová spoleაnost, Deutsche Bahn AG, Faiveley, Instituto Superior Técnico Lisboa, Mer Mec SpA, Politecnico di Milano, Réseau ferré de France, Rete ferroviaria italiana, Trenitalia SpA, Union internationale des chemins de fer, Kungliga Tekniska Högskolan

Figure 1: Structure of the EUROPACAS software.

The goal of the track-side monitoring station developed within Europac is to evaluate both compatibility and quality of a pantograph coming into a network. As shown in figure 2, existing sensors are used and the effort is put into the development of a real-time data analyser and of an expert system, allowing the end-user to assess the quality of a pantograph passing by the station and consequently to optimise maintenance.

Figure 2: Structure of the track-side monitoring station.

Finally, the on-board monitoring system aims at detecting defects in catenaries, identifying their origins and evaluating their seriousness. Its main technical characteristics are its capability of identifying and localising the defects present in the Overhead Contact Line at very high speed (up to 300 km/h) and its real-time analyser which will allow combination of human-like expertise with automation. As shown in figure 3, existing sensors are used and efforts are put into the development of the software targeted to the infrastructure managers.

Figure 3: Structure of the on-board monitoring system.

The present paper presents the project’s main results at mid-term. The first part is dedicated to the interoperable software; the second to the track-side monitoring station and the last to the on-board monitoring system.

Europacas, the Europac software

Figure 4: EUROPACAS software architecture. In red colour: some of the perturbed situations taken into account.

The software developed within Europac, named Europacas, is designed to be interoperable and to allow studying defects, singularities and extreme climatic conditions. As shown in figure 4, it consists of two independent modules, for the catenary and the pantograph, respectively. OSCAR, the Finite Element simulation tool developed by SNCF in cooperation with SDTools is used as a starting point for the development of the catenary module; and DAP3D, a general multibody software developed by IST, is the basis of the pantograph module. The pantograph-catenary contact is modeled using a unilateral penalty method and from the computational point of view, co-simulation has been retained to favour flexibility, i.e. the ability of interchanging one of the modules with another one.

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Figure 5: OSCAR / Measurements correlation. French high speed line, V=300 km/h.

As shown in figure 5, first correlation results according to the EN50318 standard are very satisfactory. Complementary developments on the catenary damping and on the droppers’ behaviour are now being realised to further improve the model. Studies on perturbed situations already begun with for instance the ability of simulating a broken dropper and thus extracting its signature, as presented in figure 6.

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Figure 6: 20Hz filtered contact force (simulation), effect of a missing dropper.

Track-side monitoring station for interoperability

The goal of the track-side monitoring station is to automatically evaluate the compatibility and quality of a pantograph coming into a network, with emphasis on the automation of this process. In order to be able to achieve these goals, a revision of the current state of the art measurement stations was necessary, as well as the conception of new techniques or sensors that can be used to gain additional knowledge about the passing pantographs. The monitoring station can be described using the schematic presented in figure 7.

Measurement system

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Decision Support System - Analysis over several measurement runs - Predictive analysis

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Figure 7: Track-side monitoring station schematic.

One important consideration during the conception phase was to make sure that the monitoring station is flexible, allowing the end user to exchange or add components that are (not) needed. In order to achieve this, the different components were chosen to have clear boundaries with clearly defined interfaces between them, allowing the end user to pick and choose those components that are of use. The flexibility and the scalability of the system have been among the top priorities when creating the concept for the system, in the sense that each component should be replaceable, not forcing the end user to accept an “everything or nothing” solution. To this end, the boundaries and interfaces between each component (and even sub-component) must be clearly defined. The system should be scalable in the sense that many measurement stations should be able to send their reports to one real time data analyser. A real time data analyser can in turn be one among several to report to one decision support system, and so on. The measurement system consists of different sensors as well as the hard- and software necessary for acquiring and saving the measurement data. As additional sensors may later prove useful, flexibility must be a high priority consideration in all stages of development. The purpose of the real-time data analyser is to analyse the collected measurement data from one single measurement. The analysis shall result in a thorough report or description of the pantograph state; not only stating whether a defect exists but rather what part or setting is most probably defective or may need tuning (if any). In order to achieve this functionality, algorithms are being developed that will take into account the measurement data collected and the prevailing weather conditions. The development of these algorithms, together with the development of algorithms and software for the decision support system, is what differentiates the monitoring system from a classical measurement station. The intelligence of the monitoring station, as well as the core of the EUROPAC project, lies in its ability not only to gather information but to analyse it and give the end user extensive information about possible defect causes. According to the principle of flexibility and scalability, special care is being taken to allow for making additions to the algorithm library, even after the discontinuation of the project.

The purpose of the decision support system, which is in fact a piece of software just as the real-time data analyser, is twofold. The system shall, through intelligent algorithms, analyse and evaluate data over several measurements, but also provide a user interface towards the end user, as presented in figure 8. The idea of analysing multiple measurement runs is based on the desire to be able to foresee or monitor how certain wear symptoms or defects develop according to known patterns. Using a kind of forecast, the end user will be able to service or exchange parts with a much higher efficiency; using synergy effects (repairing / exchanging two components at one time) or by being able to use the components longer (more exact information of when a repair or exchange is actually necessary). The multiple run analysis brings other advantages. An end user would be able to not only view the development of one single pantograph but also to view and compare pantographs within, for example, one build series.

Figure 8: Interface of the track-side monitoring station decision support system.

On board monitoring system

The current catenary inspection equipments are suffering from limitations arising from the specificity of the railway application, such as the high speed platform operation and the critical disturbances environment. Moreover, data processing and interpretation is still a time consuming task to be performed off-line by expert services before useful information for the final user can be extracted. The Europac on-board monitoring system will have the following features to overcome the current limitations: identification at high speed of the origin and type of defects; data processing of different equipment outputs according to an integrated approach; an innovative data analyser for catenary analysis; a networked data interpretation and processing software, based on expert systems; and finally data transfer to the maintenance centre in an exploitable form.

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Figure 9: Typical pantograph and coach instrumentation.

As for the track-side monitoring station, the on-board monitoring system is composed of a measurement system made of existing sensors such as the ones depicted in figure 9, of a Real-Time Data Analyser and of a Decision Support System. These modules will be strictly separated with particular emphasis on the system flexibility and scalability, as depicted in figure 10.

Figure 10: Architecture of the on-board monitoring system.

Test trials in two European countries (Czech Republic and France) will be performed to assess the prototype performances. Preliminary tests will be carried out on the Velim ring (cf. figure 11), owned by CD (VUZ), where defects will be installed in order to test the measurement system and to obtain a defect library. Final tests will then be carried out to validate the on-board monitoring system, on a French high speed line, using the SNCF high speed train TGV. The measured data will be used for validating the monitoring system and the WP1 software, and for obtaining defects signatures.

Figure 11: Velim test circuit.

Conclusion

The Europac project duration is three years, until the end of 2007. The complete specifications of the three project’s outcomes (software tool, track-side monitoring station and on-board monitoring system) have been finalised, and their implementation begun. The Europac software is already capable of simulating French, German, Italian and Swedish catenaries, as well as a large number of pantographs. The implementation of defects, singularities and climatic conditions has already begun and will be finalised during 2006. A complete user interface will then be implemented. Most of the hardware part of the track-side measurement station is implemented, and the software components are being developed, starting from existing measurement data. The on-board measurement pantograph is instrumented and ready for the measurement campaign that will be carried out on the Velim test circuit in April-May 2006. This campaign will help validating the simulation software, implementing the Real-Time Data Analyser and the Decision Support System of the on-board monitoring system and also measuring data related to defects in the pantograph, thus gathering additional information for the development of the track-side monitoring station. The Europac final results will be presented at the next World Congress on Railway Research.

Acknowledgements

The work presented here has been developed in the framework of the project EUROPAC (European Optimised Pantograph Catenary Interface, contract nº STP4-CT-2005-012440), funded by the European Commission.