Calculation of regenerative energy in DC 1500V electric railway substations

DC electric railway system with diode rectifier operates in the first quadrant of voltage-current plane and thus requires regenerative inverters which transfer the surplus regenerative power caused by regenerative braking of electric train sets into the grid. In order to install a regenerative inverter with optimum capacity, it is necessary to investigate the consumed and regenerative energy of the electric traction substations in advance. In this paper, analysis results of regenerative energy in two substations operating in Seoul line 2 and Kwangju line 1 are presented. DC line voltage and feeder currents are measured for a day to calculate consumed and regenerative power for four feeders. We calculated an amount of regenerative energy consumed in other feeders and estimated the cost reduction in energy consumption due to the reuse of regenerative energy.