Power quality improvement of DC electrified railway distribution systems using hybrid filters

DC Electrified railways play an important role for metropolitan public transportation because of high efficiency, heavy ridership and fast transportation. However, the electrified railways cause great problems for the power quality of the distribution system feeding the traction system such as injecting harmonics, reactive power compensation and low power factor issue. These problems can be solved by using a hybrid filter in the traction substations. In this paper, a modified PQ control system has been applied for the control of shunt active filter, while the passive filters are used for reducing most of the severe harmonics. The simulation is done with PSCAD/EMTDC proving the efficiency of the proposed hybrid filter structure for reducing the current harmonics, voltage and current balancing, reactive power compensation and power factor improvement