Energy loss comparison between 750 VDC and 1500 VDC power supply systems using rail power simulation

When a new transit line is to be built, apart from many other aspects, it is also necessary to study alternatives of the traction power supply system. One aspect to be studied in calculating the operational cost is the estimated level of electricity cost. If the line capacity exceeds 22000 pphpd (Passenger Per Hour Per Direction), i.e. medium sized transport capacity, train-set configuration will consist of more than 4 vehicles, and headway time between the trains will get narrower, which results in greater traction energy demand. Energy loss in a conductor is proportional to the square of the current drawn from it. As a result, in theory, doubling the voltage level reduces the energy losses to one quarter. This might not be correct due to regenerative braking energy.