Overhead Line Equipment Research Articles

A modelling approach for railway overhead line equipment asset management

The Overhead Line Equipment (OLE) is a critical sub-system of the 25kV AC overhead railway electrification system. If OLE asset management strategies can be evaluated using a whole lifecycle cost analysis that considers degradation processes and maintenance activities of the OLE components, the investment required to deliver the level of performance desired by railway customers and regulators can be based on evidence from the analysis results. A High Level Petri Net (HLPN) model, proposed in this paper, is used to simulate the degradation, failure, inspection and maintenance of the main OLE components and to calculate various statistics, associated with the cost and reliability of the system over its lifecycle. The HLPN considers all the main OLE components in a single model and it can simulate fixed frequency inspections and condition-based maintenance regimes. In order to allow the relevant processes to be modelled accurately and efficiently, the HLPN features are used, such as specific data about individual components is taken account of in the general model. The HLPN, developed using international standards, is described in detail and a framework of its analysis for reliability and lifecycle cost evaluation is proposed. In this novel whole system model different OLE component types and their instances on a line are modelled simultaneously, and the dependencies are considered in terms of opportunistic inspection and maintenance. An example HLPN for the catenary wire is used to illustrate the model, and an application of the methodology for whole lifecycle cost evaluation of a two-mile OLE line is presented.

Energy Is On Board: Energy Storage and Other Alternatives in Modern Light Railways

The traditional concept of dc traction systems for light rail applications was based in a simple dc system that was fed by ac/dc noncontrolled diode rectifier substations connected to the ac distribution network. Low-energy efficiency and controllability were not a problem. However, with the massive implementation of regenerative braking technologies in light trains and trams, the development of an effective way to manage the recovered energy became an important issue. The regenerated power injected in the system by a train in braking mode could be used only in the case where another nearby train was in traction mode. Otherwise, the regenerated power was dissipated in the dc traction system or in the rheostatic braking equipment, decreasing the overall system energy efficiency. The need for more solutions that would allow more use of the regenerated energy and increased energy efficiency in the system was the driving force for new technological developments. First, proposals were for the use of reversible substations able to give back the dc energy surplus to the ac distribution system. Then, due to energy storage cost reductions, a combination of technologies such as insulated-gate bipolar transistor (IGBT)-based reversible substations with on-board and off-board accumulation systems evolved into a reality. The use of substation-level off-board accumulation systems can also avoid the installation of reversible infrastructure, providing a high degree of controllability over the dc traction system voltage. However, higher efficiency rates are achieved when the energy storage is installed on board. In such a case, the regenerated power is used in-situ, minimizing the transmission losses. One of the main benefits of the offboard accumulation approach is the fact that many trains equipped with regenerative braking systems can take advantage of a single device. On the other hand, the use of on-board accumulation leads us toward more flexible, efficient, and dependable systems. Therefore, some manufacturers are using these kinds of on-board accumulation systems to avoid the use of overhead line equipment and to reduce the visual impact, offering catenary-free solutions.

Rehabilitation of the Victorian Connaught Tunnel for London's Crossrail project – design challenges

The Connaught Tunnel is a 19th-century brick-lined structure that has been renovated to facilitate the route of the southeast spur of London's Crossrail project from Canary Wharf to Abbey Wood. Modifications include the total replacement of the original, twin, single-track tunnels (lined in brick and cast steel) with a single, twin-track, reinforced concrete box. This was partially built in situ where the alignment passes beneath existing dock walls, and partially in cofferdam where it crosses the dock passage between the two Royal Docks (Albert and Victoria). Inverts in the original tunnels were lowered in places to accommodate the design train envelope and overhead line equipment. This paper outlines the constraints inherent in an undertaking of this nature, and describes the analytical processes that were adopted to assess the performance of the existing brick structures and the new central concrete box section.

Development of a Whole Life Cycle Cost Model for Electrification options on the UK Rail System

Projects to deliver Overhead Line Equipment (OLE) electrification on the UK rail infrastructure system presents technical challenges which the rail industry in Britain have not traditionally had to consider. Whole Life Cycle assessment provides decision makers with cost estimates for the installation phase and over the entire service life of the system, including disposal. The OLE projects face a particular problem when analysing the best option for overbridges. Much of the rail infrastructure has not traditionally had to consider overhead clearances and therefore many of the bridges are only a little taller than the rolling stock. In addition to the difficulties in assessing the Life-Cycle costs of assets that have historically been used in very limited scales, the Whole Life Cycle assessment must consider the various engineering options that are available for projects. The three competing options (bridge rebuild, track lowering, reduced clearance) are all going to have very different capital expenditure (CAPEX) and operating expenditure (OPEX) costs. This work presents a model created to predict these costs over the anticipated assessment period. The developed model predicts capital expenditures, maintenance and service disruption costs and links them to the three major assets options involved in OLE underbridges.

ACTIVE CONTROLS AND NON-INVASIVE MONITORING FOR HIGH SPEED TRAINS

International interest is growing for improving performance of the rail transport system. A crucial problem for railway companies is to prevent damages to the overhead line equipment and to pantographs. A brief overview of our research activities is addressed, in the fields of active pantographs and advanced methods for measuring the quality of the current collection for high-speed trains. The pantograph-overhead contact wire interaction is investigated by using a phototube sensor, wavelet transform applied to the line current and infrared camera. The results obtained are relevant for monitoring the quality of the current collection and for a predictive maintenance of the pantograph and of the contact line.

The German Federal Railway Class 120 Three-Phase Drive System: Service Trials

Since 1980, the German Federal Railway (DB) has been conducting service trials with five prototype Class 120 locomotives, during the course of which studies have been made of the locomotive as a whole, of the availability and reliability of individual components and of compliance with the conditions set out in the specification. These trials have shown that the basic concept and the system engineering used in this locomotive have come fully up to expectation. Such reactions on the overhead line equipment (OHLE) as have been identified have fallen well within the limits laid down. The scope for feeding power back into the OHLE will depend very much on the programme to which the locomotive is working, but is expected to be on the scale originally envisaged. The regenerative brake has proved itself as a highly reliable piece of equipment. I n terms of ride, the Class 120 has been passed for 200 km/h running. As an addendum to the specification, refinements have been made to the design of the Class 120, in order to make it a truly mixed traffic locomotive. Refinements and modifications were necessary in the power and control systems, as well as in certain components, which had to be improved in order to give better availability.

Electrification of the Tyne and Wear Metro

The Tyne and Wear Metro is the backbone of an integrated public transport system for Tyneside. The paper examines the background to the Metro, the power supply and overhead line equipment, and deals with the general technical considerations which have governed the design of the power system and equipment. Methods of constructions are also discussed, together with the control and operation of the system. Conclusions are drawn in the light of practical experience of the sections of Metro which are now operational.

Conversion of a railway system from d.c. to a.c. high-voltage operation

The paper describes the conversion from the 1500 V d.c. to the 25 kV and 6-25kV a.c. 50c/s system of electrification of the British Railways Eastern Region lines between Liverpool Street, Shenfield, Chelmsford and Southend (Victoria). The history of the projects and reasons for change are set out, together with the effect of electrification of other lines in the area. An endeavour has been made to cover in a balanced manner all principal aspects of the conversion operation from planning to conclusion, power supply, substations and switching stations, supervisory control, overhead-line equipment, rolling stock, signalling and telecommunications, civil engineering and the actual change-over sequence.It was a combined operation requiring most meticulous planning if the very heavy electric services operating over the lines concerned were not to be disrupted, with great inconvenience to hundreds of thousands of regular, daily passengers. The operation was successfully completed to a very restricted time schedule within little more than a month of the original target date owing to the unsparing efforts of many on the railway, with contractors and with the electricity supply undertakings.

The electrification of the Liverpool Street-Shenfield lines, Eastern Region—British Railways

The paper briefly surveys the history of the suburban services out of Liverpool Street station and gives the reasons for the electrification of the line to Shenfield, with an indication of the anticipated improvements.The system of electrification adopted is that with current collection from an overhead line at 1 500 volts d.c., and the paper describes the power supply arrangements, the cable transmission system, the substations, the overhead line equipment, the multiple-unit rolling stock and the car sheds.Manufacture of the equipments had commenced before the war and a certain amount of overhead-line equipment had been installed on site, but all work was suspended early in 1940. The scheme was taken in hand again after the war, and the line was opened to service on the 26th September, 1949.Estimated figures for current consumption and maximum demands are given in the paper, but the service has not been in operation for a sufficient length of time to allow these estimates to be confirmed or any operating experience to be gained with the equipments.