The Application Of Reactive Power Compensation And Harmonics Detection In Railway Power System

In modem electric power system, the problems generated by reactive power and harmonics are becoming more and more serious. Harmonics and reactive power not only deteriorate electric power quality, but also endanger system stability and economics. So more and more attention has been paid to them. The developing of power electronic technique provide a better compensation approach for harmonics, reactive power and three-phase unbalance voltage.Active Power Filter(APF) is a novel apparatus consisted of semiconductors switching devices, and is capable of compensating reactive power and eliminating harmonics at the same time. That is why it attracts so much attention. In this dissertation, the principle of APF and harmonic detection methods are introduced. And compensation effects of different current control patterns are studied. Later a new method to obtain the harmonic currents based on adaptive digital filtering is proposed. This method is simply and can be applied to voltage distortion with faster responsibility and higher measurement accuracy.In this thesis, based on analysis of harmonics and reactive power impact in-electric railway, a model for harmonics and reactive power compensation device is proposed, and design principle for this device is discussed. Results from theoretical analysis and simulation indicate that this model has better compensative features.