RICERCA ITALIANA     

IMPROVEMENT OF CURRENT TRANSMISSION FOR HIGH SPEED TRAINS BY MEANS OF ACTIVE PANTOGRAPHS AND NON-INVASIVE DIAGNOSTICS

Università di Pisa

Abstract

In case of high-speed trains, a regular current transmission in pantograph-catenary systems is a critical task. A regular current transmission in railways is more and more relevant because of European Standards about interoperability: they define the rules for an efficient transnational circulation of high-speed trains in Europe, i.e., a locomotive must be designed to freely operate inside European countries independently from the feeding voltage and frequency. A high quality current collection is characterised by a continuous contact between the pantograph and the overhead contact wire. A poor contact produces various drawbacks, including bursts of arcing: if they have a long duration, efficiency of the locomotive may reduce and an excessive wear of the pantograph strips and of the contact wire may be produced. One of the proposed solutions for achieving a high quality contact is to design servo-actuated pantographs with a control system able to regulate some relevant variables, such as the contact force, during operation. Although the use of a totally active pantograph is advantageous from the viewpoint of potential performance, the reliability of the current pickup would be strongly related to the correct operation of the control system. There exists a hybrid fail-safe solution consisting of adding some sensors and actuators to a conventional pantograph allowing non-optimal operation also in case of failure of the control system. This solution would also have the >>>

Principal Investigator

Alberto LANDI Università di PISA

Research Objectives

The development of innovative methods for improving efficiency, reliability and safety in railway system is a primary objective of the railway research. In case of high-speed trains, a regular current transmission in pantograph-catenary systems is a critical task. A regular current transmission in railways is more and more relevant because of European Standards about interoperability: they define the rules for an efficient transnational circulation of high-speed trains in Europe, i.e., a locomotive must be designed to freely operate inside European countries independently from the feeding voltage and frequency. A high quality current collection is characterised by a continuous contact between the pantograph and the overhead contact wire. A poor contact produces various drawbacks, including bursts of arcing: if they have a long duration, efficiency of the locomotive may reduce and an excessive wear of the pantograph strips and of the contact wire may be produced. One of the proposed solutions for achieving a high quality contact is to design servo-actuated pantographs with a control system able to regulate some relevant variables, such as the contact force, during operation. Although the use of a totally active pantograph is advantageous from the viewpoint of potential performance, the reliability of the current pickup would be strongly related to the correct operation of the control system. There exists a hybrid fail-safe solution consisting of adding some sensors and >>>

First Results

TASK 1 (Florence): one or more sets of kinematic parameters which define in detail the main frame mechanism. Technical report.

TASK 2 (Milan): definition of the pantograph-collector head.Technical report.

TASK 3 (Pisa): Definition of suitable parameters and of image processing techniques for IR camera. Technical report.

TASK 4 (Catania): Setup of a test-rig able to reproduce the dynamic behaviour of the pantograph-catenary system : control in the frequency range corresponding to the train span passage frequency. Technical report.

TASK 5 (Cagliari): definition of the control algorithms.Technical report.TASK 1 (Florence): Aerodynamic optimisation of the main frame. Technical report.

TASK 2A (Milan): experimental testing of new pantograph collector-heads and comparison with standard solutions,

TASK 2b: construction of a dynamometric collector strip. Technical report.

TASK 3 (Pisa): Definition and testing of algorithms able to processing IR images for diagnostic purposes. Technical report.

TASK 4 (Catania): Setup of a test-rig able to reproduce the dynamic behaviour of the pantograph-catenary system : control in the frequency range corresponding to the train passage under droppers. Technical report.

TASK 5 (Cagliari): improvement of the control algorithms and their implementation on a microprocessor. Technical report.TASK 1a (Florence) >>>

Timescale

24 months

National and international background

The quality of current transmission has a basic role especially for high-speed trains, since it represents the main limiting factor for the maximum speed; this aspect becomes more critical when the presence of more than one pantograph is required for traction. Current collection quality leads also to important consequences on the wear of the materials of the sliding contact (i.e., the contact wire from the catenary and the contact strip for the pantograph), affecting the maintenance costs and the life-time of the line: the lifetime of a over-head line might decrease from 20-25 years, to less than 10 years with irregular current collection, which often occurs for speeds higher than 200 km/h. At high-speed current collection from overhead line presents problems, well known to the railway companies, because of the loosing of a continuous contact between pantograph strips and the overhead line. Losses of contact involve mechanical, electric and electromagnetic negative consequences, such as excessive wear of pantograph and catenary, insufficient current collection, electromagnetic pollution and EMI compatibility. Usually a static load is applied to the contact strip in order to push it towards the catenary. Moreover, the resultant of the aerodynamics forces usually sums up with the static load and their value is increasing with speed. The contact force presents oscillations around the static value (i.e., its mean value) due to the dynamic interaction between the pantograph and >>>