Criteria to estimate the voltage unbalances due to high-speed railway demands

This paper has presented simple criteria to estimate the voltage unbalances due to high-speed railway demands that are generally single-phase loads. Feeding traction loads from the public power system may lead to some voltage unbalance on the latter and consequently affect the operation of its energy supply system and other equipments connected with it. Three transformer connection schemes that are commonly used in power supply systems for high-speed railways are discussed and compared. The estimating criteria have been derived and represented by simple formulae that can be easily applied to evaluate this voltage unbalance. The results are of value to related engineers and consultants especially during periods of planning and design.>