Power quality disturbances in power supply system of the subway of Rome

The paper illustrates the results of a wide power quality (PQ) survey performed on the power supply installations of the metro-transit system in Rome. The system provides two railway lines supplied at 1.5 KV DC through several AC/DC converter substations (ESS). The power supply of the system is provided at medium voltage (MV-20 kV) from five different connections to the public grid. Fourteen electrical conversion substations provide the total demand of about 20 MW of the system. The survey has involved monitoring activities aimed at identifying possible PQ problems of various natures. Voltage and current wave shapes have been monitored during several weeks. PQ indices and PQ disturbances occurrence are illustrated.