Characterization of PQ indices for an electrified metro-transit system through simulation and monitoring activities

The paper illustrates some results of a wide power quality (PQ) survey performed on the power supply installations of the metro-transit system serving the city of Rome, in Italy. The system currently includes two railway lines supplied at 1,500 V DC through AC/DC 3.7 MW rated converters. The power supply of the system is provided at medium voltage (20 kV) from rive different connections to the public grid. Fourteen electrical substations provide the total demand of about 20 MW of the system. The survey providing both simulation and monitoring activities has taken origin from an extension made on the system. The monitoring activity has been aimed also at identifying all the possible sources of PQ disturbances and their typical time-varying characteristics. Finally, some guidelines are provided for approaching similar studies for DC traction systems.