Power losses minimization in D.C. electric railways by means of traction substations coordinated voltage control

This paper suggest a way of reducing the power losses of a DC electric railway system by means of the appropriate and simultaneous voltage control of traction substations while satisfying the requirements of the European Standard EN 50163 about "Supply voltage of traction systems". The same algorithm has been also used to minimize the total energy cost of the system when different energy prices are considered in each substation. Besides, the possibility of regenerative braking is taken into account in both cases.