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Considering risks in power system operation and the consequence of different accepted risk level

Published: 20 September 2017

This project provides important new knowledge about how some of the future's challenges regarding the power supply of railways can be handled.

Sponsor: Elektra (Energimyndigheten)

Researchers: Lars Abrahamsson, LTU

Duration: 2016

The report describes the background of the postdoctoral project, and describes the purpose of the task. Economy, principals behind the project, performers, external stakeholders, industry contacts, and the reference group’s compilation are also stated.

In the large section, "the main results" the concrete produced results and experiences arising from the project are treated. The report also treats the effectiveness and impact in society.

The results are briefly about:

  • Optimal placement of energy storage in the underground network. In the study, the aim is mainly to use the energy storage in order to better exploit the braking energy. The model is general and can for example also be used to even out the load peaks over time and between rectifier stations.

  • Load sharing between substations by activating/deactivating the rotary converters and by voltage droop control (also called voltage compounding). This is simply about getting an energy efficient operation of the traction system, also the less controllable parts of it.

  • Optimal reactive power control of locomotives. The results show that for weak networks reactive power control can facilitate train motoring and regeneration, and thus lead to a more energy efficient operation. A positive side effect of this is that the traction system becomes less sensitive to outages of converter capacity.

  • A model has been developed for future feasibility analysis for power supply system limitations on optimal train operation plans calculated without regard to the electric power system.

  • A model for adaptive no-load voltage of the rectifier stations in a subway DC power system has been developed. The results can, also (though not without laying on of hands) generalize to AC fed railways.

  • A model for evaluating the traction system’s reliability with respect to the converter feeding has been developed. The model shows that a simple and good-enough measure of train power needs is to count the number of trains per traction feeding section. The goal here is to identify areas or specific substations that need to be strengthened in terms of power capacity with respect to reliability.

The overall objectives following the definitions "first area" and "second area", and the three important overall tasks have been fulfilled. Details of implementation have by natural reasons been adapted with respect to the conditions of the project and the performer.

Social effects have been mainly focused on information and knowledge, as well as networking. The project’s technical implementation is briefly described separately. Other parts of the implementation are treated implicitly in other parts of the report.

ISBN 978-91-7673-273-1