Harmonic Suppression Of The Electric Traction Load Based On DFACTS

Energy-saving is one of the basic national policies of our country for building economical society.With the rapid development of the electrified railway,the electric traction load has been one of the most important loads in the electric power system.At present,the majority of the electric locomotives are still adopting AC-DC drive mode,these electric traction loads will generate lots of harmonic currents which enter into the electric network through the traction power supply system,seriously threaten the safety and normal operation of the electric network and other devices.At the same time,they cost enormous economic losses to the railway department.To slove the problem above,the harmonic characteristic of SS4G electric locomotive is studied deeply.The active power filter based on DFACTS which is designed for SS4G electric locomotive is proposed combined with engineering application.The energy loss is decreased by suppressing the harmonic currents,which realizes the purpose of energy-saving.Firstly,electrical structure,working mechanism and control characteristic of SS4G electric locomotive are studied deeply in this paper.The simulation model of its main circuit is built and analyzed by Matlab/Simulink soft,the harmonic characteristic and energy consumption of SS4G electric locomotive are mainly studied.Secondly,the structure scheme of the active power filter applied to SS4G electric locomotive is proposed.The methods of harmonic current detection and control which are suitable for single-phase circuit are studied.The simulation models of the active power filter adopting three control approaches are built and simulated,the simulation results show that the hybrid control approach has the best effect.Finally,the system model of the active power filter applied to SS4G electric locomotive is built,the simulation experiment is made by Matlab/Simulink soft.The harmonic characteristic and energy consumption of SS4G electric locomotive before and after filtering are compared and analyzed through simulation experiment.The results show,the harmonic currents of the electric traction load decrease substantially after filtering by adopting the active power filter designed in this paper,and the energy loss also reduce,which proves that the method proposed in this paper is effective and economical.