Methods of improving the voltage regulation on 25 kV electric railways

In Australia, commercial and operating pressures are dictating the running of fewer but larger trains for a specified traffic task. The railway power supply design (and therefore the infrastructure costs) are however governed by the instantaneous power demands of the train and the spacing between trains. It is far easier to optimise infrastructure costs and achieve a high load factor on a railway power system which supplies, European style, many trains each of relatively small magnitude, than to supply a smaller number of large trains. The problems are further aggravated in Australia by the weak, radially-fed power systems and the random nature of freight train operations. The author documents a range of options which can be used, selectively, to optimise the power system design on a new electrification project, or to enhance an existing AC electrification at any voltage or frequency. On a new electrification project, these techniques have the potential to reduce the power supply infrastructure costs by about 10% compared with compared with conventional systems based on normal European practices