The liberalization of the railway market and the aim of fostering the interoperability among European countries makes the monitoring of the quality of the power (PQ) exchanged between trains and supply system even more important. At the moment, definitions, procedures and techniques for DC railway systems are under development. In this contest, the paper proposes a reference generation system able to reproduce the voltage and current waveforms experienced at pantograph by a DC 3 kV locomotive. The system is able to generate simultaneously voltage and current signals up to 10 kV peak and 1.2 kA peak respectively. The AC ripple which can be superimposed has a bandwidth of 30 kHz for the voltage and 600 Hz for the current. Moreover, it is able to reproduce several PQ events both with an accuracy, in the worst case of 1%.