mohammad ali akbari baseri - Iran University of Science and Technology, Tehran, Iran
mehdi niaki nezhad - Iran University of Science and Technology, Tehran, Iran
mohammad ali sandidzadeh - Iran University of Science and Technology, Tehran, Iran
vahid irani - Iran University of Science and Technology, Tehran, Iran

The low power factor and the voltage fluctuation are two stability problems in many ac electrified railway systems. This paper surveys the usage of several types of Flexible AC Transmission Systems (FACTS) for power quality improvements of an electrified railway system which has been consisted of phasecontrolled thyristor converters to feed the DC motor drives of their locomotives. The section of a typical single-phase 25-kV, 50Hz, electrified railway system is loaded with ac–dc thyristor-based locomotives. It is equipped with either static VAR compensator (SVC) or static synchronous compensator (STATCOM). The capability of this system as power conditioner is confirmed by using detailed simulations in MATLAB Simulink software. At first, stability problems which are created without using of these compensators are considered. Then stability investigations such as voltage profile of feeder station and analyzing of power factor steady state are conducted on the impact of these compensators on some case studies. It was found that the SVC and STATCOM considerably improve the power quality parameters of the system in below: regulation of the voltage profile and power factor improvement.

electrified railway systems, static synchronous compensator, static VAR compensator, power factor improvement, voltage regulation