Based On The Hybrid Active Power Filter To Suppress Harmonic And Compensate Reactive In Electrified Railway

The electrified railway has heavy load, fast speed, little energy consumption and environmental pollution. However, the power system of power quality has been serious polluted because of the operation of electrified railway. With China's railway electrified level improvement, the harmonic and reactive power will be greatly improved. That will give many unsafe factors to power system, and have bad effect to the economic operation of power equipment. For all that, base on the actual situation in our country, the harmonic suppression and reactive compensation in electrified railway have been researched. In this way, traction power supply system's power factor has been improved, harmonic content has been reduced, the operation of the electrified railway and the network's safety have been improved, the power equipment's utilization has been improved, the green power system's environment has been improved and the electric management method has been improved.The dangers of harmonic and reactive have been introduced. And harmonic suppression and reactive power compensation status have been summarized. In which the classification and development of the active power filter have been emphatically introduced.Base on the type of traction transformer and the each principle of harmonic transmission has been summarized. Then the modes of electric railway power supply and the types of electric locomotive have been summarized. In MATLAB simulation environment, new simulation method has been used to simulate SS8 electric locomotive. In this way, the simulation results of the dynamic harmonic currents with changing transformer lead, and the dynamic reactive power with speeding up have been got. The Fourier analysis has been used to analysis harmonic currents. This conclusion is that the electric locomotive injects odd harmonic current into grid. There is 3rd harmonic content 26%, 5th harmonic content 14%, 7th harmonic content 10% and 9th harmonic content 7%. By phase frequency chart show that locomotive not only need to reactive power compensation but also harmonic reactive power compensation. And it will influence reactive power compensation. The paper claimed that eliminate this influence by filter harmonic.The entry point is that the importance of harmonic and reactive current detection of active power filter link to it achieve the ideal state has been told. For computer programming, the mathematical analysis of smooth window iterative DFT and instantaneous reactive power theory have been done respectively. In MATLAB programming, the selected harmonics have been detected by smooth window iterative DFT, and reactive current and harmonic have been detected in time by instantaneous reactive power theory. Through the comparison of the two kinds of processing results, the paper put forward novel detection method, which i p ? iqcombines with smooth window iterative DFT. In MATLAB programming get result is that selected harmonic currents and reactive current have been got synchronous, but the precision of detection have been reduced.Base on the paper put forward the structure of the hybrid active power filter, which mathematical models have been building respectively. In detail, the situation has been divided into only effect on fundamental voltage and only effect on harmonic environment. Though MATLAB simulation method, the device of passive filter of tolerance to quality factor, which sensitivity analysis result have been got in the situation of only fundamental. The result is that the tolerance of electric capacity has high effect on quality factor .And the model under harmonic alone, Though MATLAB simulation method, hybrid active power filter not easy to occur parallel resonant grid have been validated. Finally, the ideal of reactive power compensation and harmonic suppresion effect have been got.