A Single Phase Multilevel Hybrid Power Filter for Electrified Railway Applications

To improve the power quality of traction power system, a current control method implemented on a multilevel hybrid power filter (MHPF) to compensate harmonics and reactive power is presented. Regarding the traction substation as a compensating object, the power quality of a traction substation can be improved integrally. The hybrid filter consists of a passive filter and a low-rated multilevel power converter. The passive filter works not only as a harmonic filter tuned at the 3 ^rd harmonic frequency, but also as a switching-ripple filters. The multilevel active power quality compensator uses source voltage reference to determine the compensating currents for single phase traction power systems. The rating of the switching devices for the active filter decreases with the use a multi-level inverter topology. Simulation results confirm the validity of the system and show that the adopted current control method is able to compensate reactive power and harmonics in the traction substation single phase 25 kV systems